docs: filesystems: convert coda.txt to ReST

This document has its own style. It seems to be print output
for the old matrixial printers where backspace were used to
do double prints.

For the conversion, I used several regex expressions to get
rid of some weird stuff. The patch also does almost all possible
conversions in order to get a nice output document, while keeping
it readable/editable as is:

- Add a SPDX header;
- Add a document title;
- Adjust document title;
- Adjust section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Adjust list markups;
- Mark some unumbered titles with bold font;
- Use footnoote markups;
- Add table markups;
- Use notes markups;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/25c06c40c3d7b947a131c3be124ce0e93cc00ae3.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/index.rst

@@ -63,6 +63,7 @@ Documentation for filesystem implementations.
    btrfs
    cifs/cifsroot
    ceph
+   coda
    cramfs
    debugfs
    dlmfs

MAINTAINERS

@@ -4203,7 +4203,7 @@ M:	coda@cs.cmu.edu
 L:	codalist@coda.cs.cmu.edu
 S:	Maintained
 W:	http://www.coda.cs.cmu.edu/
-F:	Documentation/filesystems/coda.txt
+F:	Documentation/filesystems/coda.rst
 F:	fs/coda/
 F:	include/linux/coda*.h
 F:	include/uapi/linux/coda*.h

fs/coda/Kconfig

@@ -15,7 +15,7 @@ config CODA_FS
 	  *client*.  You will need user level code as well, both for the
 	  client and server.  Servers are currently user level, i.e. they need
 	  no kernel support.  Please read
-	  <file:Documentation/filesystems/coda.txt> and check out the Coda
+	  <file:Documentation/filesystems/coda.rst> and check out the Coda
 	  home page <http://www.coda.cs.cmu.edu/>.
 
 	  To compile the coda client support as a module, choose M here: the