rev-parse(1): logically group options

The options section of the git-rev-parse manual page has grown
organically so that there now does not seem to be much logic behind the
ordering of the options.  It also does not make it clear that certain
options must appear first on the command line.

Address this by reorganising the options into groups with subheadings.
The text of option descriptions does not change.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-rev-parse.txt

@@ -24,9 +24,23 @@ distinguish between them.
 
 OPTIONS
 -------
+
+Operation Modes
+~~~~~~~~~~~~~~~
+
+Each of these options must appear first on the command line.
+
 --parseopt::
 	Use 'git rev-parse' in option parsing mode (see PARSEOPT section below).
 
+--sq-quote::
+	Use 'git rev-parse' in shell quoting mode (see SQ-QUOTE
+	section below). In contrast to the `--sq` option below, this
+	mode does only quoting. Nothing else is done to command input.
+
+Options for --parseopt
+~~~~~~~~~~~~~~~~~~~~~~
+
 --keep-dashdash::
 	Only meaningful in `--parseopt` mode. Tells the option parser to echo
 	out the first `--` met instead of skipping it.
@@ -36,10 +50,8 @@ OPTIONS
 	the first non-option argument.  This can be used to parse sub-commands
 	that take options themselves.
 
---sq-quote::
-	Use 'git rev-parse' in shell quoting mode (see SQ-QUOTE
-	section below). In contrast to the `--sq` option below, this
-	mode does only quoting. Nothing else is done to command input.
+Options for Filtering
+~~~~~~~~~~~~~~~~~~~~~
 
 --revs-only::
 	Do not output flags and parameters not meant for
@@ -55,6 +67,9 @@ OPTIONS
 --no-flags::
 	Do not output flag parameters.
 
+Options for Output
+~~~~~~~~~~~~~~~~~~
+
 --default <arg>::
 	If there is no parameter given by the user, use `<arg>`
 	instead.
@@ -94,6 +109,17 @@ can be used.
 	strip '{caret}' prefix from the object names that already have
 	one.
 
+--abbrev-ref[=(strict|loose)]::
+	A non-ambiguous short name of the objects name.
+	The option core.warnAmbiguousRefs is used to select the strict
+	abbreviation mode.
+
+--short::
+--short=number::
+	Instead of outputting the full SHA-1 values of object names try to
+	abbreviate them to a shorter unique name. When no length is specified
+	7 is used. The minimum length is 4.
+
 --symbolic::
 	Usually the object names are output in SHA-1 form (with
 	possible '{caret}' prefix); this option makes them output in a
@@ -107,16 +133,8 @@ can be used.
 	unfortunately named tag "master"), and show them as full
 	refnames (e.g. "refs/heads/master").
 
---abbrev-ref[=(strict|loose)]::
-	A non-ambiguous short name of the objects name.
-	The option core.warnAmbiguousRefs is used to select the strict
-	abbreviation mode.
-
---disambiguate=<prefix>::
-	Show every object whose name begins with the given prefix.
-	The <prefix> must be at least 4 hexadecimal digits long to
-	avoid listing each and every object in the repository by
-	mistake.
+Options for Objects
+~~~~~~~~~~~~~~~~~~~
 
 --all::
 	Show all refs found in `refs/`.
@@ -139,18 +157,20 @@ shown.  If the pattern does not contain a globbing character (`?`,
 	character (`?`, `*`, or `[`), it is turned into a prefix
 	match by appending `/*`.
 
---show-toplevel::
-	Show the absolute path of the top-level directory.
+--disambiguate=<prefix>::
+	Show every object whose name begins with the given prefix.
+	The <prefix> must be at least 4 hexadecimal digits long to
+	avoid listing each and every object in the repository by
+	mistake.
 
---show-prefix::
-	When the command is invoked from a subdirectory, show the
-	path of the current directory relative to the top-level
-	directory.
+Options for Files
+~~~~~~~~~~~~~~~~~
 
---show-cdup::
-	When the command is invoked from a subdirectory, show the
-	path of the top-level directory relative to the current
-	directory (typically a sequence of "../", or an empty string).
+--local-env-vars::
+	List the GIT_* environment variables that are local to the
+	repository (e.g. GIT_DIR or GIT_WORK_TREE, but not GIT_EDITOR).
+	Only the names of the variables are listed, not their value,
+	even if they are set.
 
 --git-dir::
 	Show `$GIT_DIR` if defined. Otherwise show the path to
@@ -172,17 +192,27 @@ print a message to stderr and exit with nonzero status.
 --is-bare-repository::
 	When the repository is bare print "true", otherwise "false".
 
---local-env-vars::
-	List the GIT_* environment variables that are local to the
-	repository (e.g. GIT_DIR or GIT_WORK_TREE, but not GIT_EDITOR).
-	Only the names of the variables are listed, not their value,
-	even if they are set.
+--resolve-git-dir <path>::
+	Check if <path> is a valid repository or a gitfile that
+	points at a valid repository, and print the location of the
+	repository.  If <path> is a gitfile then the resolved path
+	to the real repository is printed.
 
---short::
---short=number::
-	Instead of outputting the full SHA-1 values of object names try to
-	abbreviate them to a shorter unique name. When no length is specified
-	7 is used. The minimum length is 4.
+--show-cdup::
+	When the command is invoked from a subdirectory, show the
+	path of the top-level directory relative to the current
+	directory (typically a sequence of "../", or an empty string).
+
+--show-prefix::
+	When the command is invoked from a subdirectory, show the
+	path of the current directory relative to the top-level
+	directory.
+
+--show-toplevel::
+	Show the absolute path of the top-level directory.
+
+Other Options
+~~~~~~~~~~~~~
 
 --since=datestring::
 --after=datestring::
@@ -197,12 +227,6 @@ print a message to stderr and exit with nonzero status.
 <args>...::
 	Flags and parameters to be parsed.
 
---resolve-git-dir <path>::
-	Check if <path> is a valid repository or a gitfile that
-	points at a valid repository, and print the location of the
-	repository.  If <path> is a gitfile then the resolved path
-	to the real repository is printed.
-
 
 include::revisions.txt[]