Tweaks to the software licensing page

[imp]

Summary

Include SDPX identifiers for all licenses
Add pointer to SPDX web site
Note third party code using only spdx identifiers

This is cleanup before a more comprehensive revision of license policy
wrt SPDX identifiers.

[debdrup]

For one-sentence-per-line changes, we generally like to keep them as separate commits.
However, I think it's okay for this commit since you're changing so little.

That being said, there's a single I've spotted.

Once fixed, assuming it builds, you can commit and push it. :)

website/content/en/internal/software-license.adoc

164–165

These two need to made into links, cf. the AsciiDoctor quick reference.

[imp]

udpate, per review. Drop one of the two links since it's only pseudo link.

[debdrup]

Looks good to me, so assuming it builds, you're good to go. :)

[hrs]

website/content/en/internal/software-license.adoc

30

Using SPDX ID to refer to a license in the followed sentences after the first appearance might be more consistent. I mean s/new Apache License/new Apache-2.0/.

35

s/BSD+Patent License/BSD-2-Clause-Patent/g

39

s/CDDL/CDDL-1.1/g