btrfs-progs: docs: add major level headings to Kernel-by-version

[ci skip]

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

Author: kdave

Documentation/Kernel-by-version.rst

@@ -3,11 +3,8 @@ Changes (kernel/version)
 
 Summary of kernel changes for each version.
 
-6.x
----
-
 6.0 (Oct 2022)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.0-rc1 <https://git.kernel.org/linus/353767e4aaeb7bc818273dfacbb01dd36a9db47a>`__,
@@ -101,7 +98,7 @@ Notable fixes:
   repair happen
 
 6.1 (Dec 2022)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.1-rc1 <https://git.kernel.org/linus/76e45035348c247a70ed50eb29a9906657e4444f>`__,
@@ -186,7 +183,7 @@ Core:
   flushing, buffered write
 
 6.2 (Feb 2023)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.2-rc1 <https://git.kernel.org/linus/149c51f876322d9bfbd5e2d6ffae7aff3d794384>`__,
@@ -248,7 +245,7 @@ Fixes:
 - limit number of send clones by maximum memory allocated
 
 6.3 (Apr 2023)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.3-rc1 <https://git.kernel.org/linus/885ce48739189fac6645ff42d736ee0de0b5917d>`__,
@@ -312,7 +309,7 @@ Fixes:
   work queues (since 6.0)
 
 6.4 (Jun 2023)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.4-rc1 <https://git.kernel.org/linus/85d7ab2463822a4ab096c0b7b59feec962552572>`__,
@@ -369,7 +366,7 @@ Core changes:
    truncating items
 
 6.5 (Aug 2023)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.5-rc1 <https://git.kernel.org/linus/cc423f6337d0a5ff1906f3b3d465d28c0d1705f6>`__,
@@ -398,7 +395,7 @@ User visible changes:
    the zones are reset as needed
 
 6.6 (Oct 2023)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.6-rc1 <https://git.kernel.org/linus/547635c6ac47c7556d6954935b189defe90422f7>`__,
@@ -429,7 +426,7 @@ Core:
 - v0 extent handling completely removed, deprecated long time ago
 
 6.7 (Jan 2024)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.7-rc1 <https://git.kernel.org/linus/d5acbc60fafbe0fc94c552ce916dd592cd4c6371>`__,
@@ -504,7 +501,7 @@ Core changes:
   devices), this allows temp_fsid to work
 
 6.8 (Mar 2024)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.8-rc1 <https://git.kernel.org/linus/affc5af36bbb62073b6aaa4f4459b38937ff5331>`__,
@@ -563,7 +560,7 @@ Fixes:
   create chunks that would not be allowed on sequential zones
 
 6.9 (May 2024)
-^^^^^^^^^^^^^^
+--------------
 
 Pull requests:
 `v6.9-rc1 (1) <https://git.kernel.org/linus/43a7548e28a6df12a6170421d9d016c576010baa>`__,
@@ -603,7 +600,7 @@ Other notable changes:
 - additional validation of devices by major:minor numbers
 
 6.10 (Jul 2024)
-^^^^^^^^^^^^^^^
+---------------
 
 Pull requests:
 `v6.10-rc1 (1) <https://git.kernel.org/linus/a3d1f54d7aa4c3be2c6a10768d4ffa1dcb620da9>`__,
@@ -638,7 +635,7 @@ Notable fixes or changes:
 - extent map shrinker, allow memory consumption reduction for direct io loads
 
 6.11 (Sep 2024)
-^^^^^^^^^^^^^^^
+---------------
 
 Pull requests:
 `v6.11-rc1 (1) <https://git.kernel.org/linus/a1b547f0f217cfb06af7eb4ce8488b02d83a0370>`__,
@@ -701,7 +698,7 @@ Other notable changes or fixes:
 - in zoned mode, detect unexpected zone write pointer change
 
 6.12 (Nov 2024)
-^^^^^^^^^^^^^^^
+---------------
 
 Pull requests:
 `v6.12-rc1 <https://git.kernel.org/linus/7a40974fd0efa3698de4c6d1d0ee0436bcc4445d>`__,
@@ -742,7 +739,7 @@ Cleanups and refactoring:
 - introduce auto free for btrfs_path structure, use for the simple cases
 
 6.13 (Jan 2025)
-^^^^^^^^^^^^^^^
+---------------
 
 Pull requests:
 `v6.13-rc1 <https://git.kernel.org/linus/c14a8a4c04c5859322eb5801db662b56b2294f67>`__,
@@ -811,7 +808,7 @@ Core changes:
   - lockdep assertions
 
 6.14 (Mar 2025)
-^^^^^^^^^^^^^^^
+---------------
 
 Pull requests:
 `v6.14-rc1 <https://git.kernel.org/linus/0eb4aaa230d725fa9b1cd758c0f17abca5597af6>`__,
@@ -881,7 +878,7 @@ Core:
   - code moved to new files
 
 6.15 (May 2025)
-^^^^^^^^^^^^^^^
+---------------
 
 Pull requests:
 `v6.15-rc1 <https://git.kernel.org/linus/fd71def6d9abc5ae362fb9995d46049b7b0ed391>`__,
@@ -947,7 +944,7 @@ Core:
 - more preparations for large folio support
 
 6.16 (Jul 2025)
-^^^^^^^^^^^^^^^
+---------------
 
 `v6.16-rc1 <https://git.kernel.org/linus/5e82ed5ca4b510e0ff53af1e12e94e6aa1fe5a93>`__,
 `v6.16-rc1 <https://git.kernel.org/linus/a56baa225308e697163e74bae0cc623a294073d4>`__,