lib: Use Locking: term in docs

This is easier to `git grep` etc. versus ad-hoc English.  Although
we still have some English for the prepare_transaction/commit which
acquire/release in separate phases.

Closes: #1572
Approved by: jlebon

src/libostree/ostree-repo-prune.c

@@ -193,7 +193,7 @@ _ostree_repo_prune_tmp (OstreeRepo *self,
  * targeting that commit; otherwise any static delta of non existing commits are
  * deleted.
  *
- * This function takes an exclusive lock on the @self repository.
+ * Locking: exclusive
  */
 gboolean
 ostree_repo_prune_static_deltas (OstreeRepo *self, const char *commit,
@@ -326,7 +326,7 @@ repo_prune_internal (OstreeRepo        *self,
  * statistics on objects that would be deleted, without actually
  * deleting them.
  *
- * This function takes an exclusive lock on the @self repository.
+ * Locking: exclusive
  */
 gboolean
 ostree_repo_prune (OstreeRepo        *self,
@@ -438,7 +438,7 @@ ostree_repo_prune (OstreeRepo        *self,
  * The %OSTREE_REPO_PRUNE_FLAGS_NO_PRUNE flag may be specified to just determine
  * statistics on objects that would be deleted, without actually deleting them.
  *
- * This function takes an exclusive lock on the @self repository.
+ * Locking: exclusive
  */
 gboolean
 ostree_repo_prune_from_reachable (OstreeRepo        *self,