Rename "Privacy considerations" to "Procedures for mitigating privacy concerns"

[henbos]

There already exists a "Security and Privacy Considerations" section later in the document, so this was a confusing title.
From comment, but that PR merged already:

@alvestrand

This needs to have a reason to go here rather than in "security and privacy considerations" at the end of the document.

I suggest using the title "Procedures for mitigating privacy concerns" and adding a reference to this section in the "Security and privacy considerations" section.

[henbos]

done