[PATCH 4/4] git-prompt.sh: add missing information in comments

["Eduardo R. D'Avila" <erdavila@gmail.com>]

Mention that the command below is needed for prompt
in ZSH with PS1:
  setopt PROMPT_SUBST

Make it clear that colored prompt is only available
in PROMPT_COMMAND mode.

Signed-off-by: Eduardo R. D'Avila <erdavila@gmail.com>
---
5	4	contrib/completion/git-prompt.sh
 contrib/completion/git-prompt.sh | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 70515cc..3ab2a69 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -13,10 +13,10 @@
 #    3a) Change your PS1 to call __git_ps1 as
 #        command-substitution:
 #        Bash: PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
-#        ZSH:  PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '
+#        ZSH:  setopt PROMPT_SUBST ; PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '
 #        the optional argument will be used as format string.
-#    3b) Alternatively, if you are using bash, __git_ps1 can be
-#        used for PROMPT_COMMAND with two parameters, <pre> and
+#    3b) Alternatively, if you are using Bash or ZSH, __git_ps1 can
+#        be used for PROMPT_COMMAND with two parameters, <pre> and
 #        <post>, which are strings you would put in $PS1 before
 #        and after the status string generated by the git-prompt
 #        machinery.  e.g.
@@ -78,7 +78,8 @@
 #
 # If you would like a colored hint about the current dirty state, set
 # GIT_PS1_SHOWCOLORHINTS to a nonempty value. The colors are based on
-# the colored output of "git status -sb".
+# the colored output of "git status -sb" and are available only when
+# using __git_ps1 for PROMPT_COMMAND.
 
 # __gitdir accepts 0 or 1 arguments (i.e., location)
 # returns location of .git repo
-- 
1.8.3.1.487.g28387b2