In 7171d8c15f ("upload-pack: send symbolic ref information as
capability"), we added a symref capability to the pack protocol, but it
was never documented. Adapt the patch notes from that commit and add
them to the capabilities documentation.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 Documentation/technical/protocol-capabilities.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/technical/protocol-capabilities.txt b/Documentation/technical/protocol-capabilities.txt
index 332d209b58..0ccdbadbe9 100644
--- a/Documentation/technical/protocol-capabilities.txt
+++ b/Documentation/technical/protocol-capabilities.txt
@@ -172,6 +172,20 @@ agent strings are purely informative for statistics and debugging
 purposes, and MUST NOT be used to programmatically assume the presence
 or absence of particular features.
 
+symref
+------
+
+This parameterized capability is used to inform the receiver which symbolic ref
+points to which ref; for example, "symref=HEAD:refs/heads/master" tells the
+receiver that HEAD points to master. This capability can be repeated to
+represent multiple symrefs.
+
+Servers SHOULD include this capability for the HEAD symref if it is one of the
+refs being sent.
+
+Clients MAY use the parameters from this capability to select the proper initial
+branch when cloning a repository.
+
 shallow
 -------
 
-- 
2.20.1.791.gb4d0f1c61a-goog