completion: document __gitcomp()

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 888e8e10ccd932df3aa8f30a3d83441d5485fc30..45cbd2b94094d4ef22b92b004e904dfe5903dd2e 100755 (executable)
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -485,8 +485,13 @@ _get_comp_words_by_ref ()
 fi
 fi
 
-# __gitcomp accepts 1, 2, 3, or 4 arguments
-# generates completion reply with compgen
+# Generates completion reply with compgen, appending a space to possible
+# completion words, if necessary.
+# It accepts 1 to 4 arguments:
+# 1: List of possible completion words.
+# 2: A prefix to be added to each possible completion word (optional).
+# 3: Generate possible completion matches for this word (optional).
+# 4: A suffix to be appended to each possible completion word (optional).
 __gitcomp ()
 {
        local cur_="$cur"