Specifyc details or reference for the "vcs_url" default qualifier

[pombredanne]

The spec has this TODO: "TODO: incorporate the details from SPDX here."

• purl-spec/PURL-SPECIFICATION.rst

  Lines 450 to 455 in 64a8585

  	- ``vcs_url`` is an extra URL for a package version control system URL to
  	optionally qualify a ``purl``. The syntax for this URL should be as defined in
  	Python pip or the SPDX specification. See
  	https://github.com/spdx/spdx-spec/blob/cfa1b9d08903/chapters/3-package-information.md#37-package-download-location
  	- TODO: incorporate the details from SPDX here.

This is about some bits of the SPDX spec that I contributed and initially stole from the Python "pip" documentation and code.

The actual details with too many examples are there:

• https://github.com/spdx/spdx-spec/blob/cfa1b9d08903befdf03e669da6472707b7b60cb9/chapters/3-package-information.md?plain=1#L225-L391