We were following it about half of the time and we even added it to our
former `.mdlrc` file. However, for some reason, MDL doesn't detect this
rule when specified in the `.mdlrc` file, so we didn't notice we weren't
following it in many cases.
Now that we're using a style file to configure MDL, we can enable this
rule again and apply it, since now MDL correctly includes it in its
report.
Not sure whether it's a good idea to end a heading with a question mark.
When in doubt, we usually keep the code as it is now, so that's what
we're doing.
This way we'll be able to customize some of the rules, which doesn't
seem to be possible when using the `.mdlrc` file.
For simplification purposes, instead of including all rules one by one,
we're excluding the few rules we don't use.
