Adds a note about the new acquire behavior for lock holders.

CHANGELOG.md

@@ -59,6 +59,8 @@ IMPROVEMENTS:
 * Enables the `/v1/internal/ui/*` endpoints, even if `-ui-dir` isn't set
   [GH-1215]
 * Added HTTP method to Consul's log output for better debugging [GH-1270]
+* Lock holders can "?acquire" a key again with the same session to update
+  its contents without releasing the lock [GH-1291]
 * Improved an O(n^2) algorithm in the agent's catalog sync code [GH-1296]
 * Switched to net-rpc-msgpackrpc to reduce RPC overhead [GH-1307]
 * Removes all uses of the http package's default client and transport in