[PATCH] completion: clarify support for short options and arguments

The list of supported completions in the header of the file was
mostly written a long time ago when Shawn added the initial version
of this script in 2006.  The list explicitly states that we complete
"common --long-options", which implies that we do not complete
not-so-common ones and single letter options (this text dates back
to May 2007).

Update the description to explicitly state that single-letter
options are not completed.  Also, document that arguments to options
are completed, even for single-letter options (e.g., "git -c <TAB>"
offers configuration variables).

Signed-off-by: Junio C Hamano <redacted>
---
 contrib/completion/git-completion.bash | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git c/contrib/completion/git-completion.bash w/contrib/completion/git-completion.bash
index 73abea31b4..538dff1ee5 100644
--- c/contrib/completion/git-completion.bash
+++ w/contrib/completion/git-completion.bash

@@ -13,7 +13,8 @@
 #    *) git email aliases for git-send-email
 #    *) tree paths within 'ref:path/to/file' expressions
 #    *) file paths within current working directory and index
-#    *) common --long-options
+#    *) common --long-options but not single-letter options
+#    *) arguments to long and single-letter options
 #
 # To use these routines:
 #