sync: Added -g as a short option for --no-content

I anticipate that if sync is transitioned to syncing content by default,
people will want a short option. And in repositories where
annex.synccontent = true, they already would. And pull and push sync
content by default, so a short option is useful with them too.

Mnemonic: -g makes only git data be synced
Also, -a makes only annex data be synced.

Would have preferred -c, which would complement -C, but it
was already taken to set git configs.

Sponsored-by: Noam Kremen on Patreon

CHANGELOG

@@ -57,6 +57,7 @@ git-annex (10.20230408) UNRELEASED; urgency=medium
     --content. With --no-pull, avoid downloading content, and with
     --no-push avoid uploading content. This was done before, but
     inconsistently.
+  * sync: Added -g as a short option for --no-content.
   * uninit: Avoid buffering the names of all annexed files in memory.
 
  -- Joey Hess <id@joeyh.name>  Sat, 08 Apr 2023 13:57:18 -0400

Command/Sync.hs

@@ -181,6 +181,7 @@ optParser mode desc = SyncOptions
 		)
 	<*> switch
 		( long "no-content"
+		<> short 'g'
 		<> help "do not transfer annexed file contents"
 		)
 	<*> many (strOption

doc/git-annex-pull.mdwn

@@ -67,9 +67,9 @@ See [[git-annex-preferred-content]](1).
   When this is combined with --no-content, only the git-annex branch
   will be pulled.
 
-* `--no-content`, `--content`
+* `--no-content, `-g`, `--content`
 
-  Use `--no-content` to avoid downloading (and dropping)
+  Use `--no-content` or `-g` to avoid downloading (and dropping)
   the content of annexed files.
 
   If you often use `--no-content`, you can set the `annex.synccontent`

doc/git-annex-push.mdwn

@@ -76,10 +76,10 @@ See [[git-annex-preferred-content]](1).
   When this is combined with --no-content, only the git-annex branch
   will be pulled.
 
-* `--no-content`, `--content`
+* `--no-content`, `-g`, `--content`
 
-  Use `--no-content` to avoid uploading (and dropping) the content of annexed
-  files.
+  Use `--no-content` or `-g` to avoid uploading (and dropping) the content
+  of annexed files.
 
   If you often use `--no-content`, you can set the `annex.synccontent`
   configuration to false to prevent uploading content by default.

doc/git-annex-sync.mdwn

@@ -19,11 +19,14 @@ content by default. This may change in a future version of git-annex.
 
 # OPTIONS
 
-* `--content`, `--no-content`
+* `--content`, `--no-content`, `-g`
 
   The --content option causes the content of annexed files
   to also be pulled and pushed.
 
+  The --no-content and -g options cause the content of annexed files to
+  not be pulled and pushed.
+
   The `annex.synccontent` configuration can be set to true to make
   `--content` be enabled by default.