This grows a new option inside of rustdoc to add the ability to submit examples
to an external website. If the `--markdown-playground-url` command line option
or crate doc attribute `html_playground_url` is present, then examples will have
a button on hover to submit the code to the playground specified.
This commit enables submission of example code to play.rust-lang.org. The code
submitted is that which is tested by rustdoc, not necessarily the exact code
shown in the example.
Closes#14654
This converts it to be very similar to crates.mk, with a single list of
the documentation items creating all the necessary bits and pieces.
Changes include:
- rustdoc is used to render HTML & test standalone docs
- documentation building now obeys NO_REBUILD=1
- testing standalone docs now obeys NO_REBUILD=1
- L10N is slightly less broken (in particular, it shares dependencies
and code with the rest of the code)
- PDFs can be built for all documentation items, not just tutorial and
manual
- removes the obsolete & unused extract-tests.py script
- adjust the CSS for standalone docs to use the rustdoc syntax
highlighting
