[PATCH 4/5] Documentation: ext4: blockgroup: Add explicit title heading

[Bagas Sanjaya <bagasdotme@gmail.com>]

Block groups documentation has three, first-level section headings.
These headings' text become toctree entries and the first one "Layout"
becomes docs title in the output, which isn't conveying the docs
contents.

Add explicit title heading and demote the rest.

Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
---
 Documentation/filesystems/ext4/blockgroup.rst | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/Documentation/filesystems/ext4/blockgroup.rst b/Documentation/filesystems/ext4/blockgroup.rst
index ed5a5cac6d40e1..7cbf0b2b778eab 100644
--- a/Documentation/filesystems/ext4/blockgroup.rst
+++ b/Documentation/filesystems/ext4/blockgroup.rst
@@ -1,7 +1,10 @@
 .. SPDX-License-Identifier: GPL-2.0
 
+Block Groups
+------------
+
 Layout
-------
+~~~~~~
 
 The layout of a standard block group is approximately as follows (each
 of these fields is discussed in a separate section below):
@@ -60,7 +63,7 @@ groups (flex_bg). Leftover space is used for file data blocks, indirect
 block maps, extent tree blocks, and extended attributes.
 
 Flexible Block Groups
----------------------
+~~~~~~~~~~~~~~~~~~~~~
 
 Starting in ext4, there is a new feature called flexible block groups
 (flex_bg). In a flex_bg, several block groups are tied together as one
@@ -78,7 +81,7 @@ if flex_bg is enabled. The number of block groups that make up a
 flex_bg is given by 2 ^ ``sb.s_log_groups_per_flex``.
 
 Meta Block Groups
------------------
+~~~~~~~~~~~~~~~~~
 
 Without the option META_BG, for safety concerns, all block group
 descriptors copies are kept in the first block group. Given the default
@@ -117,7 +120,7 @@ Please see an important note about ``BLOCK_UNINIT`` in the section about
 block and inode bitmaps.
 
 Lazy Block Group Initialization
--------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 A new feature for ext4 are three block group descriptor flags that
 enable mkfs to skip initializing other parts of the block group
-- 
An old man doll... just what I always wanted! - Clara