Documentation: fix --color option formatting

Add missing colon in two places to fix formatting of options.

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-for-each-ref.txt

@@ -57,7 +57,7 @@ OPTIONS
 	`xx`; for example `%00` interpolates to `\0` (NUL),
 	`%09` to `\t` (TAB) and `%0a` to `\n` (LF).
 
---color[=<when>]:
+--color[=<when>]::
 	Respect any colors specified in the `--format` option. The
 	`<when>` field must be one of `always`, `never`, or `auto` (if
 	`<when>` is absent, behave as if `always` was given).

Documentation/git-tag.txt

@@ -115,7 +115,7 @@ options for details.
 	variable if it exists, or lexicographic order otherwise. See
 	linkgit:git-config[1].
 
---color[=<when>]:
+--color[=<when>]::
 	Respect any colors specified in the `--format` option. The
 	`<when>` field must be one of `always`, `never`, or `auto` (if
 	`<when>` is absent, behave as if `always` was given).