all: move description of C files below the copyright and license

src/plugins/irc/irc-command.c

@@ -1,6 +1,4 @@
 /*
- * irc-command.c - IRC commands
- *
  * SPDX-FileCopyrightText: 2003-2025 Sébastien Helleu <flashcode@flashtux.org>
  * SPDX-FileCopyrightText: 2006 Emmanuel Bouthenot <kolter@openics.org>
  *
@@ -22,6 +20,8 @@
  * along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/* IRC commands */
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>