Allow manual platform selection for tailored documentation

[jsejcksn]

See #157. Opening this issue per @pacocoursey’s comment:

Manual selection is a good idea, if you still feel strongly about adding it as a feature please open a new issue.

[amanjagdev]

Hello there, @jsejcksn. I also believe it would be a promising idea to include this on the website.

Furthermore, Maintainers, I'd like to work on this issue. Should I get started on this?