Update draft release notes to 1.7.6

I think we are almost there for the feature freeze.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/RelNotes/1.7.6.txt

@@ -53,11 +53,6 @@ Updates since v1.7.5
  * "git commit" learned a "--patch" option to directly jump to the
    per-hunk selection UI of the interactive mode.
 
- * "git diff -C -C" used to disable the rename detection entirely when
-   there are too many copy candidate paths in the tree; now it falls
-   back to "-C" when doing so would keep the copy candidate paths
-   under the rename detection limit.
-
  * "git diff" and its family of commands learned --dirstat=0 to show
    directories that contribute less than 0.1% of changes.
 
@@ -72,6 +67,8 @@ Updates since v1.7.5
    characters in it, e.g. "Junio C. Hamano" <jch@example.com>.  Earlier
    it was up to the user to do this when using its output.
 
+ * "git format-patch" can take an empty --subject-prefix now.
+
  * "git log" and friends learned a new "--notes" option to replace the
    "--show-notes" option.  Unlike "--show-notes", "--notes=<ref>" does
    not imply showing the default notes.
@@ -93,9 +90,20 @@ Updates since v1.7.5
 
  * p4-import (from contrib) learned a new option --preserve-user.
 
+ * "git read-tree -m" learned "--dry-run" option that reports if a merge
+   would fail without touching the index nor the working tree.
+
  * "git rebase" that does not specify on top of which branch to rebase
    the current branch now uses @{upstream} of the current branch.
 
+ * "git rebase" finished either normally or with --abort did not
+   update the reflog for HEAD to record the event to come back to
+   where it started from.
+
+ * "git remote add -t only-this-branch --mirror=fetch" is now allowed. Earlier
+   a fetch-mode mirror meant mirror everything, but now it only means refs are
+   not renamed.
+
  * "git rev-list --count" used with "--cherry-mark" counts the cherry-picked
    commits separately, producing more a useful output.
 
@@ -116,11 +124,6 @@ Fixes since v1.7.5
 Unless otherwise noted, all the fixes in 1.7.5.X maintenance track are
 included in this release.
 
- * The single-key mode of "git add -p" was easily fooled into thinking
-   that it was told to add everthing ('a') when up-arrow was pressed by
-   mistake.
-   (merge tr/add-i-no-escape later)
-
  * "git config" used to choke with an insanely long line.
    (merge ef/maint-strbuf-init later)