myfirstcontrib: add 'psuh' to command-list.txt

Users can discover commands and their brief usage by running 'git help
git' or 'git help -a'; both of these pages list all available commands
based on the contents of 'command-list.txt'. That means adding a new
command there is an important part of the new command process, and
therefore belongs in the new command tutorial.

Teach new users how to add their command, and include a brief overview
of how to discover which attributes to place on the command in the list.

Since 'git psuh' prints some workspace info, doesn't modify anything,
and is targeted as a user-facing porcelain command, list it as a
'mainporcelain' and 'info' command.

As the usage string is required to generate this documentation, don't
add the command to the list until after the usage string is added to the
tutorial.

Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/MyFirstContribution.txt

@@ -534,6 +534,28 @@ you want to pass as a parameter something which would usually be interpreted as
 a flag.) `parse_options()` will terminate parsing when it reaches `--` and give
 you the rest of the options afterwards, untouched.
 
+Now that you have a usage hint, you can teach Git how to show it in the general
+command list shown by `git help git` or `git help -a`, which is generated from
+`command-list.txt`. Find the line for 'git-pull' so you can add your 'git-psuh'
+line above it in alphabetical order. Now, we can add some attributes about the
+command which impacts where it shows up in the aforementioned help commands. The
+top of `command-list.txt` shares some information about what each attribute
+means; in those help pages, the commands are sorted according to these
+attributes. `git psuh` is user-facing, or porcelain - so we will mark it as
+"mainporcelain". For "mainporcelain" commands, the comments at the top of
+`command-list.txt` indicate we can also optionally add an attribute from another
+list; since `git psuh` shows some information about the user's workspace but
+doesn't modify anything, let's mark it as "info". Make sure to keep your
+attributes in the same style as the rest of `command-list.txt` using spaces to
+align and delineate them:
+
+----
+git-prune-packed                        plumbingmanipulators
+git-psuh                                mainporcelain		info
+git-pull                                mainporcelain           remote
+git-push                                mainporcelain           remote
+----
+
 Build again. Now, when you run with `-h`, you should see your usage printed and
 your command terminated before anything else interesting happens. Great!