doc: clone: add a note about git 2.41+ and fetch.hideRefs

It's unusable for large mirrors, otherwise.

diff --git a/Documentation/public-inbox-clone.pod b/Documentation/public-inbox-clone.pod
index 152fed7303a6883c039e95c533c7253b9dfb1196..c3254fa07e5bd15d0d7eaf713647e9e1705c3609 100644 (file)
--- a/Documentation/public-inbox-clone.pod
+++ b/Documentation/public-inbox-clone.pod
@@ -127,7 +127,11 @@ as relative to the C<DESTINATION> directory.  If only C<--manifest=>
 is specified where C<FILE> is an empty string (C<"">), then C<manifest.js.gz>
 (C<$DESTINATION/manifest.js.gz>) is the implied value of C<FILE>.
 
-This is a new option in public-inbox 2.0+
+When updating manifests with many forks using the same objstore,
+git 2.41+ is highly recommended for performance as we automatically
+use the C<fetch.hideRefs> feature to speed up negotiation.
+
+C<--manifest=> is a new option in public-inbox 2.0+
 
 =item --remote-manifest=URL|RELATIVE_PATH