Add documentation for 1.7.0

[jbonofre]

Anticipating a little the 1.7.0 release.

Checklist

• 🛡️ Don't disclose security issues! (contact security@apache.org)
• 🔗 Clearly explained why the changes are needed, or linked related issues: Fixes #
• 🧪 Added/updated tests with good coverage, or manually tested (and explained how)
• 💡 Added comments for complex logic
• 🧾 Updated CHANGELOG.md (if needed)
• 📚 Updated documentation in site/content/in-dev/unreleased (if needed)

[ayushtkn]

Thanx @jbonofre for chasing this & the release :-)

We have to update the ChangeLog and doap files to reflect 1.7.0 as well, maybe as another PR

polaris/CHANGELOG.md

Line 28 in 28634d9

## [Unreleased]

polaris/doap.rdf

Line 49 in 28634d9

<name>1.6.0</name>

[jbonofre]

@ayushtkn good point. I will create a couple of other PRs: the update for 1.7.0, another one to include part of the release process (automatic).