btrfs-progs: docs: convert btrfs-map-logical to rst

Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/btrfs-map-logical.rst

@@ -0,0 +1,38 @@
+btrfs-map-logical(8)
+====================
+
+SYNOPSIS
+--------
+
+**btrfs-map-logical** <options> <device>
+
+DESCRIPTION
+-----------
+
+**btrfs-map-logical** can be used to find out what the physical offsets are
+on the mirrors, the result is dumped to stdout by default.
+
+Mainly used for debug purpose.
+
+OPTIONS
+-------
+
+-l|--logical <logical_num>
+        Logical extent to map.
+-c|--copy <copy>
+        Copy of the extent to read(usually 1 or 2).
+-o|--output <filename>
+        Output file to hold the extent.
+-b|--bytes <bytes>
+        Number of bytes to read.
+
+EXIT STATUS
+-----------
+
+**btrfs-map-logical** will return 0 if no error happened.
+If any problems happened, 1 will be returned.
+
+SEE ALSO
+--------
+
+``mkfs.btrfs(8)``

Documentation/conf.py

@@ -61,4 +61,5 @@ man_pages = [
     ('btrfs-check', 'btrfs-check', 'check or repair a btrfs filesystem', '', 8),
     ('btrfs-balance', 'btrfs-balance', 'balance block groups on a btrfs filesystem', '', 8),
     ('btrfs-subvolume', 'btrfs-subvolume', 'manage btrfs subvolumes', '', 8),
+    ('btrfs-map-logical', 'btrfs-map-logical', 'map btrfs logical extent to physical extent', '', 8),
 ]

Documentation/man-index.rst

@@ -14,6 +14,7 @@ Manual pages
    btrfs-find-root
    btrfs-image
    btrfs-inspect-internal
+   btrfs-map-logical
    btrfs-property
    btrfs-qgroup
    btrfs-quota