[PATCH v4] archive: describe compression level option

[Bagas Sanjaya <bagasdotme@gmail.com>]

Describe the only extra option in `git archive`, that is the compression
level option. Previously this option is only described for zip backend;
add description also for tar backend.

Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
---
 Changes since v3 [1]:
     - use smaller size - slower time term
     - use <digit> and <number> for compression level

 [1]: https://lore.kernel.org/git/xmqq8ryqxo72.fsf@gitster.g/T/#t
 Documentation/git-archive.txt | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-archive.txt b/Documentation/git-archive.txt
index 9f8172828d..ecfae7e268 100644
--- a/Documentation/git-archive.txt
+++ b/Documentation/git-archive.txt
@@ -93,12 +93,19 @@ BACKEND EXTRA OPTIONS
 
 zip
 ~~~
--0::
-	Store the files instead of deflating them.
--9::
-	Highest and slowest compression level.  You can specify any
-	number from 1 to 9 to adjust compression speed and ratio.
+-<digit>::
+	Regulate compression level using the specified <digit>. Higher
+	values enables smaller size at the expense of slower time.
+	Supported values are from `-0` (store-only) to `-9` (best ratio).
+	Default is `-6` if isn't specified.
 
+tar
+~~~
+-<number>::
+	Specify compression level. The value will be passed to the
+	compression command configured in `tar.<format>.command`. See
+	manual page of the configured command for the list of supported
+	levels and the default level if this option isn't specified.
 
 CONFIGURATION
 -------------

base-commit: f443b226ca681d87a3a31e245a70e6bc2769123c
-- 
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