Document --FLAKY-- section of PHPTs

[cmb69]

The given example might not be the best one, since it actually wouldn't need the --FLAKY-- section, but it's the only one we currently have.

[cmb69]

I've planning a couple more updates, including documenting the "flakyif", soon.

[iluuu1994]

Very nice, thank you :)

[cmb69]

I've added a commit to document the "flaky" convention for SKIPIF sections.

[derickr]

I think it is good to document these (obviously), but as per https://news-web.php.net/php.internals/125482, I think it would be great if we move the docs on qa.php.net into the normal documentation (php/doc-en), or to https://github.com/php/php-src/tree/master/docs ?

[cmb69]

@derickr, sure. I haven't changed my mind from https://externals.io/message/125480#125482 (not even from https://externals.io/message/118219). But as long as we haven't agreed on a new home for the docs (it's not only about the home, but also the markup is completely different), I'd like to keep the info on qa.php.net up-to-date.

[iluuu1994]

As run-tests.php is primarily targeted at php-src and extension developers, https://php.github.io/php-src/ makes the most sense to me. But it makes sense to update this here, before we have anything concrete going on.