The Doxygen "Modules" page is not very illuminative, as different parts
of the API are mixed together and not all parts are included.

Try to address this:

Put all parts of the public API to some Doxygen group, usually one group
per header file. Use short, systematic names.

Make these groups sub-groups of a few top-level groups, roughly
corresponding to the different logical parts of the API (core, impl,
stream, filter, spa, utilities).

Peter Hutterer authored May 25, 2021 and Wim Taymans committed May 26, 2021

Flatten the hierarchy a bit to make it easier to handle.

My vim/git setup wants to fix those on every commit which gets a bit annoying,
let's just remove them: sed -i 's/ *$//g' $(git ls-files doc)

Note that the order of the includes matters - that's how doxygen will sort
them. There is no specific structure other than the include order - one reason
why the headers are being changed. Without polluting the markdown files with
doxygen commands we cannot use \subpage, so all files convert to a regular
\page and are listed as flat hierarchy in the sidebar (and in Related Pages).

Changing the headers at least provides some visual grouping with comon
prefixes.

Andrea Gelmini authored Apr 30, 2021 and Wim Taymans committed Apr 30, 2021

Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>

Link Mauve authored Jul 22, 2020 and Wim Taymans committed Aug 17, 2020

This tool detects and fixes common English spelling mistakes, with
generally very few mistakes.

Here is the command I used to generate this commit.  There were a few
changes that had to be done manually, and of course adding the ignore
file:
```shell
codespell -I .codespell-ignore -x .codespell-ignore -w
```

I didn’t add it to the CI, but this would be a good place for it.