Minor corrections to release notes

Update section about warning when leaving a detached head.

Also fix a few indentations that weren't like the rest of the file.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/RelNotes-1.5.0.txt

@@ -291,12 +291,10 @@ Updates in v1.5.0 since v1.4.4 series
    reset" to jump to arbitrary commit, while still keeping your
    HEAD detached.
 
-   Going back to attached state (i.e. on a particular branch) by
-   "git checkout $branch" can lose the current stat you arrived
-   in these ways, and "git checkout" refuses when the detached
-   HEAD is not pointed by any existing ref (an existing branch,
-   a remote tracking branch or a tag).  This safety can be
-   overridden with "git checkout -f $branch".
+   Remember that a detached state is volatile, i.e. it will be forgotten
+   as soon as you move away from it with the checkout or reset command,
+   unless a branch is created from it as mentioned above.  It is also
+   possible to rescue a lost detached state from the HEAD reflog.
 
 
 * Packed refs