git-rev-parse.txt: Add more examples for caret and colon

Several items in the caret, colon and friends section contain examples
already. Make sure they all come with examples, and that examples come
early so that they serve as a visual guide, as well.
Signed-off-by: NMichael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-rev-parse.txt

@@ -256,7 +256,7 @@ the `$GIT_DIR/refs` directory or from the `$GIT_DIR/packed-refs` file.
   the branch the ref is set to build on top of.  Missing ref defaults
   to the current branch.
 
-* A suffix '{caret}' to a revision parameter means the first parent of
+* A suffix '{caret}' to a revision parameter (e.g. 'HEAD{caret}') means the first parent of
   that commit object.  '{caret}<n>' means the <n>th parent (i.e.
   'rev{caret}'
   is equivalent to 'rev{caret}1').  As a special rule,
@@ -282,23 +282,24 @@ the `$GIT_DIR/refs` directory or from the `$GIT_DIR/packed-refs` file.
   and dereference the tag recursively until a non-tag object is
   found.
 
-* A colon, followed by a slash, followed by a text: this names
+* A colon, followed by a slash, followed by a text (e.g. `:/fix nasty bug`): this names
   a commit whose commit message starts with the specified text.
   This name returns the youngest matching commit which is
   reachable from any ref.  If the commit message starts with a
   '!', you have to repeat that;  the special sequence ':/!',
   followed by something else than '!' is reserved for now.
 
-* A suffix ':' followed by a path; this names the blob or tree
+* A suffix ':' followed by a path (e.g. `HEAD:README`); this names the blob or tree
   at the given path in the tree-ish object named by the part
-  before the colon. ":path" (with an empty part before the colon)
+  before the colon.
+  ':path' (with an empty part before the colon, e.g. `:README`)
   is a special case of the syntax described next: content
   recorded in the index at the given path.
 
 * A colon, optionally followed by a stage number (0 to 3) and a
-  colon, followed by a path; this names a blob object in the
-  index at the given path.  Missing stage number (and the colon
-  that follows it) names a stage 0 entry. During a merge, stage
+  colon, followed by a path (e.g. `:0:README`); this names a blob object in the
+  index at the given path. Missing stage number (and the colon
+  that follows it, e.g. `:README`) names a stage 0 entry. During a merge, stage
   1 is the common ancestor, stage 2 is the target branch's version
   (typically the current branch), and stage 3 is the version from
   the branch being merged.