Documentation/filesystems: ramfs-rootfs-initramfs: use :Author:

Use the :Author: markup instead of making it a chapter heading.
This cleans up the table of contents for this file.

Fixes: 7f46a240 ("[PATCH] ramfs, rootfs, and initramfs docs")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Rob Landley <rob@landley.net>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230508055928.3548-1-rdunlap@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/ramfs-rootfs-initramfs.rst

@@ -6,8 +6,7 @@ Ramfs, rootfs and initramfs
 
 October 17, 2005
 
-Rob Landley <rob@landley.net>
-=============================
+:Author: Rob Landley <rob@landley.net>
 
 What is ramfs?
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