docs: filesystems: convert isofs.txt to ReST

- Add a SPDX header;
- Add a document title;
- Some whitespace fixes and new line breaks;
- Add table markups;
- Add lists markups;
- Add it to filesystems/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/ec16dc09d0c23bb0c1af3d3f33a96896083a1d36.1581955849.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/index.rst

@@ -71,6 +71,7 @@ Documentation for filesystem implementations.
    hfsplus
    hpfs
    inotify
+   isofs
    fuse
    overlayfs
    virtiofs

Documentation/filesystems/isofs.txt → Documentation/filesystems/isofs.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+==================
+ISO9660 Filesystem
+==================
+
 Mount options that are the same as for msdos and vfat partitions.
 
+  =========	========================================================
   gid=nnn	All files in the partition will be in group nnn.
   uid=nnn	All files in the partition will be owned by user id nnn.
   umask=nnn	The permission mask (see umask(1)) for the partition.
+  =========	========================================================
 
 Mount options that are the same as vfat partitions. These are only useful
 when using discs encoded using Microsoft's Joliet extensions.
-  iocharset=name Character set to use for converting from Unicode to
+
+ ==============	=============================================================
+ iocharset=name Character set to use for converting from Unicode to
 		ASCII.  Joliet filenames are stored in Unicode format, but
 		Unix for the most part doesn't know how to deal with Unicode.
 		There is also an option of doing UTF-8 translations with the
 		utf8 option.
   utf8          Encode Unicode names in UTF-8 format. Default is no.
+ ==============	=============================================================
 
 Mount options unique to the isofs filesystem.
-  block=512     Set the block size for the disk to 512 bytes
-  block=1024    Set the block size for the disk to 1024 bytes
-  block=2048    Set the block size for the disk to 2048 bytes
-  check=relaxed Matches filenames with different cases
-  check=strict  Matches only filenames with the exact same case
-  cruft         Try to handle badly formatted CDs.
-  map=off       Do not map non-Rock Ridge filenames to lower case
-  map=normal    Map non-Rock Ridge filenames to lower case
-  map=acorn     As map=normal but also apply Acorn extensions if present
-  mode=xxx      Sets the permissions on files to xxx unless Rock Ridge
-		extensions set the permissions otherwise
-  dmode=xxx     Sets the permissions on directories to xxx unless Rock Ridge
-		extensions set the permissions otherwise
+
+ ================= ============================================================
+  block=512        Set the block size for the disk to 512 bytes
+  block=1024       Set the block size for the disk to 1024 bytes
+  block=2048       Set the block size for the disk to 2048 bytes
+  check=relaxed    Matches filenames with different cases
+  check=strict     Matches only filenames with the exact same case
+  cruft            Try to handle badly formatted CDs.
+  map=off          Do not map non-Rock Ridge filenames to lower case
+  map=normal       Map non-Rock Ridge filenames to lower case
+  map=acorn        As map=normal but also apply Acorn extensions if present
+  mode=xxx         Sets the permissions on files to xxx unless Rock Ridge
+		   extensions set the permissions otherwise
+  dmode=xxx        Sets the permissions on directories to xxx unless Rock Ridge
+		   extensions set the permissions otherwise
   overriderockperm Set permissions on files and directories according to
-		'mode' and 'dmode' even though Rock Ridge extensions are
-		present.
-  nojoliet      Ignore Joliet extensions if they are present.
-  norock        Ignore Rock Ridge extensions if they are present.
-  hide		Completely strip hidden files from the file system.
-  showassoc	Show files marked with the 'associated' bit
-  unhide	Deprecated; showing hidden files is now default;
-		If given, it is a synonym for 'showassoc' which will
-		recreate previous unhide behavior
-  session=x     Select number of session on multisession CD
-  sbsector=xxx  Session begins from sector xxx
+		   'mode' and 'dmode' even though Rock Ridge extensions are
+		   present.
+  nojoliet         Ignore Joliet extensions if they are present.
+  norock           Ignore Rock Ridge extensions if they are present.
+  hide		   Completely strip hidden files from the file system.
+  showassoc	   Show files marked with the 'associated' bit
+  unhide	   Deprecated; showing hidden files is now default;
+		   If given, it is a synonym for 'showassoc' which will
+		   recreate previous unhide behavior
+  session=x        Select number of session on multisession CD
+  sbsector=xxx     Session begins from sector xxx
+ ================= ============================================================
 
 Recommended documents about ISO 9660 standard are located at:
-http://www.y-adagio.com/
-ftp://ftp.ecma.ch/ecma-st/Ecma-119.pdf
-Quoting from the PDF "This 2nd Edition of Standard ECMA-119 is technically 
+
+- http://www.y-adagio.com/
+- ftp://ftp.ecma.ch/ecma-st/Ecma-119.pdf
+
+Quoting from the PDF "This 2nd Edition of Standard ECMA-119 is technically
 identical with ISO 9660.", so it is a valid and gratis substitute of the
 official ISO specification.