git-gui: add a readme

It is a good idea to have a readme so people finding the project can
know more about it, and know how they can get involved.

Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>
Acked-by: Bert Wesarg <bert.wesarg@googlemail.com>

README.md

@@ -0,0 +1,174 @@
+# Git GUI - A graphical user interface for Git
+
+Git GUI allows you to use the [Git source control management
+tools](https://git-scm.com/) via a GUI. This includes staging, committing,
+adding, pushing, etc. It can also be used as a blame viewer, a tree browser,
+and a citool (make exactly one commit before exiting and returning to shell).
+More details about Git GUI can be found in its manual page by either running
+`man git-gui`, or by visiting the [online manual
+page](https://git-scm.com/docs/git-gui).
+
+Git GUI was initially written by Shawn O. Pearce, and is distributed with the
+standard Git installation.
+
+# Building and installing
+
+You need to have the following dependencies installed before you begin:
+
+- Git
+- Tcl
+- Tk
+- wish
+- Gitk (needed for browsing history)
+- msgfmt
+
+Most of Git GUI is written in Tcl, so there is no compilation involved. Still,
+some things do need to be done (mostly some substitutions), so you do need to
+"build" it.
+
+You can build Git GUI using:
+
+```
+make
+```
+
+And then install it using:
+
+```
+make install
+```
+
+You probably need to have root/admin permissions to install.
+
+# Contributing
+
+The project is currently maintained by Pratyush Yadav over at
+https://github.com/prati0100/git-gui. Even though the project is hosted at
+GitHub, the development does not happen over GitHub Issues and Pull Requests.
+Instead, an email based workflow is used. The Git mailing list
+[git@vger.kernel.org](mailto:git@vger.kernel.org) is where the patches are
+discussed and reviewed.
+
+More information about the Git mailing list and instructions to subscribe can
+be found [here](https://git.wiki.kernel.org/index.php/GitCommunity).
+
+## Sending your changes
+
+Since the development happens over email, you need to send in your commits in
+text format. Commits can be converted to emails via the two tools provided by
+Git: `git-send-email` and `git-format-patch`.
+
+You can use `git-format-patch` to generate patches in mbox format from your
+commits that can then be sent via email. Let's say you are working on a branch
+called 'foo' that was created on top of 'master'. You can run:
+
+```
+git format-patch -o output_dir master..foo
+```
+
+to convert all the extra commits in 'foo' into a set of patches saved in the
+folder `output_dir`.
+
+If you are sending multiple patches, it is recommended to include a cover
+letter. A cover letter is an email explaining in brief what the series is
+supposed to do. A cover letter template can be generated by passing
+`--cover-letter` to `git-format-patch`.
+
+After you send your patches, you might get a review suggesting some changes.
+Make those changes, and re-send your patch(es) in reply to the first patch of
+your initial version. Also please mention the version of the patch. This can be
+done by passing `-v X` to `git-format-patch`, where 'X' is the version number
+of the patch(es).
+
+### Using git-send-email
+
+You can use `git-send-email` to send patches generated via `git-format-patch`.
+While you can directly send patches via `git-send-email`, it is recommended
+that you first use `git-format-patch` to generate the emails, audit them, and
+then send them via `git-send-email`.
+
+A pretty good guide to configuring and using `git-send-email` can be found
+[here](https://www.freedesktop.org/wiki/Software/PulseAudio/HowToUseGitSendEmail/)
+
+### Using your email client
+
+If your email client supports sending mbox format emails, you can use
+`git-format-patch` to get an mbox file for each commit, and then send them. If
+there is more than one patch in the series, then all patches after the first
+patch (or the cover letter) need to be sent as replies to the first.
+`git-send-email` does this by default.
+
+### Using GitGitGadget
+
+Since some people prefer a GitHub pull request based workflow, they can use
+[GitGitGadget](https://gitgitgadget.github.io/) to send in patches. The tool
+was originally written for sending patches to the Git project, but it now also
+supports sending patches for git-gui.
+
+Instructions for using GitGitGadget to send git-gui patches, courtesy of
+Johannes Schindelin:
+
+If you don't already have a fork of the [git/git](https://github.com/git/git)
+repo, you need to make one. Then clone your fork:
+
+```
+git clone https://github.com/<your-username>/git
+```
+
+Then add GitGitGadget as a remote:
+
+```
+git remote add gitgitgadget https://github.com/gitgitgadget/git
+```
+
+Then fetch the git-gui branch:
+
+```
+git fetch gitgitgadget git-gui/master
+```
+
+Then create a new branch based on git-gui/master:
+
+```
+git checkout -b <your-branch-name> git-gui/master
+```
+
+Make whatever commits you need to, push them to your fork, and then head over
+to https://github.com/gitgitgadget/git/pulls and open a Pull Request targeting
+git-gui/master.
+
+GitGitGadget will welcome you with a (hopefully) helpful message.
+
+## Signing off
+
+You need to sign off your commits before sending them to the list. You can do
+that by passing the `-s` option to `git-commit`. You can also use the "Sign
+Off" option in Git GUI.
+
+A sign-off is a simple 'Signed-off-by: A U Thor \<author@example.com\>' line at
+the end of the commit message, after your explanation of the commit.
+
+A sign-off means that you are legally allowed to send the code, and it serves
+as a certificate of origin. More information can be found at
+[developercertificate.org](https://developercertificate.org/).
+
+## Responding to review comments
+
+It is quite likely your patches will get review comments. Those comments are
+sent on the Git mailing list as replies to your patch, and you will usually be
+Cc'ed in those replies.
+
+You are expected to respond by either explaining your code further to convince
+the reviewer what you are doing is correct, or acknowledge the comments and
+re-send the patches with those comments addressed.
+
+Some tips for those not familiar with communication on a mailing list:
+
+- Use only plain text emails. No HTML at all.
+- Wrap lines at around 75 characters.
+- Do not send attachments. If you do need to send some files, consider using a
+  hosting service, and paste the link in your email.
+- Do not [top post](http://www.idallen.com/topposting.html).
+- Always "reply all". Keep all correspondents and the list in Cc. If you reply
+  directly to a reviewer, and not Cc the list, other people would not be able
+  to chime in.