Add @requires

[jbrubake]

Add file- or function-level @requires. Each @requires is formatted as an unordered list item and can be multiple lines. I did notice some oddities with indentation of multi-line @requires and putting them before the @description but this was consistent with how @std* is handled and @requires re-uses that code.

From the added examples:

# @file libexample
...
# @requires foo
# @requires bar

# @description My super function.
...
# @requires Some very specific requirements
...
say-hello() {

is formatted as:

libexample

...

Requires

• foo
• bar
  ...

say-hello

My super function
...

Requires

• Some very specific requirements

[GB609]

Hey. Thanks for the PRs. I'll have a look at it as soon as i can, i'm a bit more busy with regular work than i'd like to be.

[GB609]

Thanks again for the contribution. This is actually an annotation I was planning to add as well.
There's only one small change i'd like you to make.