Documentation/diff-options.txt: unify options

Instead of listing short option (e.g. "-U<n>") as a shorthand for its
longer counterpart (e.g. "--unified=<n>"), list the synonyms together.  It
saves one indirection to find what the reader wants.

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

Documentation/diff-options.txt

@@ -19,16 +19,12 @@ endif::git-format-patch[]
 
 ifndef::git-format-patch[]
 -p::
+-u::
 	Generate patch (see section on generating patches).
 	{git-diff? This is the default.}
 endif::git-format-patch[]
 
--u::
-	Synonym for "-p".
-
 -U<n>::
-	Shorthand for "--unified=<n>".
-
 --unified=<n>::
 	Generate diffs with <n> lines of context instead of
 	the usual three. Implies "-p".
@@ -190,31 +186,25 @@ endif::git-format-patch[]
 	can name which subdirectory to make the output relative
 	to by giving a <path> as an argument.
 
+-a::
 --text::
 	Treat all files as text.
 
--a::
-	Shorthand for "--text".
-
 --ignore-space-at-eol::
 	Ignore changes in whitespace at EOL.
 
+-b::
 --ignore-space-change::
 	Ignore changes in amount of whitespace.  This ignores whitespace
 	at line end, and considers all other sequences of one or
 	more whitespace characters to be equivalent.
 
--b::
-	Shorthand for "--ignore-space-change".
-
+-w::
 --ignore-all-space::
 	Ignore whitespace when comparing lines.  This ignores
 	differences even if one line has whitespace where the other
 	line has none.
 
--w::
-	Shorthand for "--ignore-all-space".
-
 --exit-code::
 	Make the program exit with codes similar to diff(1).
 	That is, it exits with 1 if there were differences and