[PATCH 8 of 8 V7] help: add documentation about bookmark part

[Stanislau Hlebik]

# HG changeset patch
# User Stanislau Hlebik <stash at fb.com>
# Date 1478095405 25200
#      Wed Nov 02 07:03:25 2016 -0700
# Branch stable
# Node ID 5ed1eda9bf3e92dd6037028a0202690dc845efa2
# Parent  c2a9f675fac55522bb954ea81c29fa0158106214
help: add documentation about bookmark part

diff --git a/mercurial/help/internals/bundles.txt b/mercurial/help/internals/bundles.txt
--- a/mercurial/help/internals/bundles.txt
+++ b/mercurial/help/internals/bundles.txt
@@ -92,3 +92,32 @@
 ``HGS1UN`` support was added as an experimental feature in version 3.6
 (released November 2015) as part of the initial offering of the *clone
 bundles* feature.
+
+Bundle2 parts
+=============
+
+Bundle2 may contain many different pieces of information. These pieces are
+called parts.
+
+Bookmarks part
+--------------
+
+This part contains information about bookmarks. Part consists of many entries.
+Each entry describes one bookmark. Entry format:
+
+4 bytes
+  bookmark size
+1 byte
+  boolean. True if node is empty, False otherwise
+20 bytes (optional)
+  node. Present only if previous field is True
+
+Modes:
+
+1. 'ignore' - do not apply any changes to the repo, just decode the passed
+bookmarks. Will be used to list bookmarks in remote repo.
+2. 'diverge' - apply bookmark changes to the repo. Create divergent bookmarks if
+there is a non-fastforward move. Will be used during pull.
+3. 'apply' - apply bookmark changes to the repo. Overwrite current bookmark node
+if there is a non-fastforward move. Will be used during push.
+