doc: build: fix gen_compile_commands section level

The 2 subsections of this page ("Compatible IDEs" and "Usage") are using
the same header level as the title (with "===").
Because of this, they always appear in the HTML rendered ToC.

Drop the subsections one level lower by replacing "=" by "-".
This fixes the HTML rendering.

Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

doc/build/gen_compile_commands.rst

@@ -42,7 +42,7 @@ needed for it to be usable by the LSP, unless you set a name for the database
 other than it's default one (compile_commands.json).
 
 Compatible IDEs
-===============
+---------------
 
 Several popular integrated development environments (IDEs) support the use
 of JSON compilation databases for C/C++ development, making it easier to
@@ -73,7 +73,7 @@ compile_commands.json in the root of the repository should suffice to enable
 code navigation.
 
 Usage
-=====
+-----
 
 For further details on the script's options, please refer to its help message,
 as in the example below.