Documentation does not render lists inside of [info] tags correctly

[cotpat]

Lists seem to break detection of at least the closing [/info] tag. This may or may not be related to the lack of a newline after the last list item. Due to the closing tag not being detected correctly, subsequent tags (such as [notice]) will not render correctly either. This persists until the next [/info] tag is encountered.

The issue is visible e.g. on the doc page for templating, just underneath the linked header (starting with the Foo example list).

Source code for that, in case that page gets updated:

[info]
Arguments passed into methods can be any non-array literal type (not just strings), e.g:

- `$Foo(1)` will pass `1` as an int
- `$Foo(0.5)` will pass `0.5` as a float
- `$Foo(true)` will pass `true` as a boolean
- `$Foo(null)` will pass `null` as a null primitive
- `$Foo("param")`, `$Foo('param')`, and `$Foo(param)` will all pass `'param'` as a string. It is recommended that you always use quotes when passing a string for clarity
[/info]

[GuySartorelli]

This happens because the [/info] closing tag is technically inside the list, so the regex in https://github.com/silverstripe/doc.silverstripe.org/blob/master/src/utils/cleanCalloutTags.ts doesn't capture it correctly.

We might have to start doing something a little more sophisticated here. silverstripe/documentation-lint#15 has some suggestions we might want to look into.

We could alternatively just implement silverstripe/documentation-lint#15 and have part of the linting rules be that there's an empty linebreak before the closing tag - in that case we wouldn't need to fix the actual bug.

[emteknetnz]

Duplicate of #282