Add explanation of CSP settings

[sebbASF]

The new CSP tool looks useful, but will users know what all the different options are for?
It woulf be useful to add descriptions and/or links to documentation for them.

[cottage14]

The documentation will be in place before the tool becomes publicly available.

[sebbASF]

I learnt of the tool via this issue:

https://issues.apache.org/jira/browse/INFRA-26638?focusedCommentId=17936653&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17936653

[cottage14]

The CSP tool is no more, replaced by a how-to page https://infra.apache.org/tools/csp.html. Closing this issue as it is no longer relevant.