DOC: configuration: document AWS-LC compatibility restrictions

DOC: configuration: document AWS-LC compatibility restrictions

The configuration manual does not explicitly identify several SSL keywords
and sample fetches that are unavailable with AWS-LC. This leaves users
without compatibility information when selecting an SSL library or
configuring an AWS-LC build.

Add compatibility notes to the affected entries, stating the minimum
OpenSSL version and the lack of AWS-LC support. This is a documentation
change only; runtime behavior is unchanged.

That should fix #3532.

This should be backported to maintained branches with AWS-LC support (as
far as 3.0). Note that some keyword may not exists in previous versions.