Documentation/config: default for color.* is color.ui

Since 4c7f181 (make color.ui default to 'auto', 2013-06-10), the
default for color.* when nothing is set is 'auto' and we still claimed
that the default was 'false'. Be more precise by saying explicitly
that the default is to follow color.ui, and recall that the default is
'auto' to avoid one indirection for the reader.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -924,7 +924,8 @@ color.branch::
 	A boolean to enable/disable color in the output of
 	linkgit:git-branch[1]. May be set to `always`,
 	`false` (or `never`) or `auto` (or `true`), in which case colors are used
-	only when the output is to a terminal. Defaults to false.
+	only when the output is to a terminal. If unset, then the
+	value of `color.ui` is used (`auto` by default).
 
 color.branch.<slot>::
 	Use customized color for branch coloration. `<slot>` is one of
@@ -939,7 +940,8 @@ color.diff::
 	linkgit:git-log[1], and linkgit:git-show[1] will use color
 	for all patches.  If it is set to `true` or `auto`, those
 	commands will only use color when output is to the terminal.
-	Defaults to false.
+	If unset, then the value of `color.ui` is used (`auto` by
+	default).
 +
 This does not affect linkgit:git-format-patch[1] or the
 'git-diff-{asterisk}' plumbing commands.  Can be overridden on the
@@ -962,7 +964,8 @@ color.decorate.<slot>::
 color.grep::
 	When set to `always`, always highlight matches.  When `false` (or
 	`never`), never.  When set to `true` or `auto`, use color only
-	when the output is written to the terminal.  Defaults to `false`.
+	when the output is written to the terminal.  If unset, then the
+	value of `color.ui` is used (`auto` by default).
 
 color.grep.<slot>::
 	Use customized color for grep colorization.  `<slot>` specifies which
@@ -995,7 +998,8 @@ color.interactive::
 	and displays (such as those used by "git-add --interactive" and
 	"git-clean --interactive"). When false (or `never`), never.
 	When set to `true` or `auto`, use colors only when the output is
-	to the terminal. Defaults to false.
+	to the terminal. If unset, then the value of `color.ui` is
+	used (`auto` by default).
 
 color.interactive.<slot>::
 	Use customized color for 'git add --interactive' and 'git clean
@@ -1011,13 +1015,15 @@ color.showBranch::
 	A boolean to enable/disable color in the output of
 	linkgit:git-show-branch[1]. May be set to `always`,
 	`false` (or `never`) or `auto` (or `true`), in which case colors are used
-	only when the output is to a terminal. Defaults to false.
+	only when the output is to a terminal. If unset, then the
+	value of `color.ui` is used (`auto` by default).
 
 color.status::
 	A boolean to enable/disable color in the output of
 	linkgit:git-status[1]. May be set to `always`,
 	`false` (or `never`) or `auto` (or `true`), in which case colors are used
-	only when the output is to a terminal. Defaults to false.
+	only when the output is to a terminal. If unset, then the
+	value of `color.ui` is used (`auto` by default).
 
 color.status.<slot>::
 	Use customized color for status colorization. `<slot>` is