Add comment explaining BGWORKER_BYPASS_ALLOWCONN

Suggested by Michael Paquier

src/include/postmaster/bgworker.h

@@ -145,9 +145,15 @@ extern void BackgroundWorkerInitializeConnection(const char *dbname, const char
 /* Just like the above, but specifying database and user by OID. */
 extern void BackgroundWorkerInitializeConnectionByOid(Oid dboid, Oid useroid, uint32 flags);
 
-/* Flags to BackgroundWorkerInitializeConnection et al */
+/*
+ * Flags to BackgroundWorkerInitializeConnection et al
+ *
+ *
+ * Allow bypassing datallowconn restrictions when connecting to database
+ */
 #define BGWORKER_BYPASS_ALLOWCONN 1
 
+
 /* Block/unblock signals in a background worker process */
 extern void BackgroundWorkerBlockSignals(void);
 extern void BackgroundWorkerUnblockSignals(void);