General docs improvements for v3.0 (#2280)

* Split the docs into sections

* Split the options page into two pages - so the reference is more clean

* Reorder/Tidy up this 'deliver' page to make auto-deploy more obvious

* Fix up some links

* Merge the platform docs into a single page to clean up the navbar.

* Split the setup page to make a page dedicated to CI setup

* Move general platform-specific information into the platforms page

* Tidy up the platforms page

* Remove some redundancy in the cpp/platforms docs

* Clarify this section

* Move another FAQ entry to the platforms page

* Remove some out-of-date entries from the FAQ

* A few corrections to the options page

* Fix some broken links

* Improve the Docker references

* Update bump version filename

* Improve options TOC information density

* whitespace

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

* Convert the normal test invocation to `pytest ./tests`, not placeholder

---------

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

test/test_emulation.py

@@ -32,7 +32,7 @@ def test(tmp_path, request):
         project_dir,
         add_env={
             "CIBW_TEST_REQUIRES": "pytest",
-            "CIBW_TEST_COMMAND": "pytest {project}/test",
+            "CIBW_TEST_COMMAND": "pytest ./test",
             "CIBW_ARCHS": archs,
         },
     )