btrfs-progs: docs: fix sphinx code-block warnings

There are several warnings regarding the absence of an argument for the
code-block directive on some build servers using python3-sphinx 0.2.2-17.

For example:

Making all in Documentation
    [SPHINX] man
ch-subvolume-intro.rst:141: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.

.. code-block::

   27 21 0:19 /subv1 /mnt rw,relatime - btrfs /dev/sda rw,space_cache

 Etc...

Add the none argument.

[ci skip]

Signed-off-by: Anand Jain <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Documentation/Tree-checker.rst

@@ -30,7 +30,7 @@ fine.
 
 A message may look like:
 
-.. code-block::
+.. code-block:: none
 
    [ 1716.823895] BTRFS critical (device vdb): corrupt leaf: root=18446744073709551607 block=38092800 slot=0, invalid key objectid: has 1 expect 6 or [256, 18446744073709551360] or 18446744073709551604
    [ 1716.829499] BTRFS info (device vdb): leaf 38092800 gen 19 total ptrs 4 free space 15851 owner 18446744073709551607
@@ -54,7 +54,7 @@ checksum is found to be valid. This protects against changes to the metadata
 that could possibly also update the checksum, less likely to happen accidentally
 but rather due to intentional corruption or fuzzing.
 
-.. code-block::
+.. code-block:: none
 
    [ 4823.612832] BTRFS critical (device vdb): corrupt leaf: root=7 block=30474240 slot=0, invalid nritems, have 0 should not be 0 for non-root leaf
    [ 4823.616798] BTRFS error (device vdb): block=30474240 read time tree block corruption detected

Documentation/ch-subvolume-intro.rst

@@ -138,7 +138,7 @@ Mounting a read-write snapshot as read-only is possible and will not change the
 The name of the mounted subvolume is stored in file :file:`/proc/self/mountinfo` in
 the 4th column:
 
-.. code-block::
+.. code-block:: none
 
    27 21 0:19 /subv1 /mnt rw,relatime - btrfs /dev/sda rw,space_cache
               ^^^^^^

Documentation/dev/Developer-s-FAQ.rst

@@ -178,7 +178,7 @@ For the next iteration, add a short description of the changes made, under the
 first **---** (triple dash) marker in the patch. For example (see also Example
 3):
 
-.. code-block::
+.. code-block:: none
 
    ---
    V3: renamed variable

Documentation/dev/Experimental.rst

@@ -11,7 +11,7 @@ filed as issues.
 
 In the code use it like:
 
-.. code-block::
+.. code-block:: none
 
     if (EXPERIMENTAL) {
         ...
@@ -22,7 +22,7 @@ where it would break default build.
 
 Or:
 
-.. code-block::
+.. code-block:: none
 
     #if EXPERIMENTAL
     ...

Documentation/dev/dev-btrfs-design.rst

@@ -15,7 +15,7 @@ The Btrfs btree provides a generic facility to store a variety of data
 types. Internally it only knows about three data structures: keys,
 items, and a block header:
 
-.. code-block::
+.. code-block:: none
 
    struct btrfs_header {
            u8 csum[32];
@@ -30,15 +30,15 @@ items, and a block header:
            u8 level;
    }
 
-.. code-block::
+.. code-block:: none
 
    struct btrfs_disk_key {
           __le64 objectid;
           u8 type;
           __le64 offset;
    }
 
-.. code-block::
+.. code-block:: none
 
    struct btrfs_item {
           struct btrfs_disk_key key;
@@ -311,7 +311,7 @@ field of the root block may be different from the objectid of the
 snapshot. So, when dropping references on tree roots, the objectid of
 the root structure is always used. When a backref is deleted:
 
-.. code-block::
+.. code-block:: none
 
    if backref was for a tree root:
         root_objectid = root->root_key.objectid

Documentation/trouble-index.rst

@@ -12,7 +12,7 @@ Error: parent transid verify error
 Reason: result of a failed internal consistency check of the filesystem's metadata.
 Type: permanent
 
-.. code-block::
+.. code-block:: none
 
    [ 4007.489730] BTRFS error (device vdb): parent transid verify failed on 30736384 wanted 10 found 8
 
@@ -59,7 +59,7 @@ persisted and possibly making old copies available.
 The most obvious way how to exhaust space is to create a file until the data
 chunks are full:
 
-.. code-block::
+.. code-block:: none
 
    $ df -h .
    Filesystem      Size  Used Avail Use% Mounted on
@@ -98,7 +98,7 @@ action is possible. If not, ENOSPC is returned.
 Error: unable to start balance with target metadata profile
 -----------------------------------------------------------
 
-.. code-block::
+.. code-block:: none
 
    unable to start balance with target metadata profile 32
 
@@ -111,7 +111,7 @@ Error: balance will reduce metadata integrity
 
 The full message in system log
 
-.. code-block::
+.. code-block:: none
 
    balance will reduce metadata integrity, use force if you want this
 
@@ -126,7 +126,7 @@ The preferred way is to use the :command:`wipefs` utility that is part of the
 *util-linux* package. Running the command with the device will not destroy
 the data, just list the detected filesystems:
 
-.. code-block::
+.. code-block:: none
 
    # wipefs /dev/sda
    offset               type
@@ -137,7 +137,7 @@ the data, just list the detected filesystems:
 Remove the filesystem signature at a given offset or wipe all recognized
 signatures on the device:
 
-.. code-block::
+.. code-block:: none
 
    # wipefs -o 0x10040 /dev/sda
    8 bytes [5f 42 48 52 66 53 5f 4d] erased at offset 0x10040 (btrfs)
@@ -172,15 +172,15 @@ at 64MiB, the third one at 256GiB. The following lines reset the signature
 on all the three copies:
 
 
-.. code-block::
+.. code-block:: none
 
    # dd if=/dev/zero bs=1 count=8 of=/dev/sda seek=$((64*1024+64))
    # dd if=/dev/zero bs=1 count=8 of=/dev/sda seek=$((64*1024*1024+64))
    # dd if=/dev/zero bs=1 count=8 of=/dev/sda seek=$((256*1024*1024*1024+64))
 
 If you want to restore the super block signatures:
 
-.. code-block::
+.. code-block:: none
 
    # echo "_BHRfS_M" | dd bs=1 count=8 of=/dev/sda seek=$((64*1024+64))
    # echo "_BHRfS_M" | dd bs=1 count=8 of=/dev/sda seek=$((64*1024*1024+64))