This PR adds a note to the Alternator TTL section to specify in which Open Source and Enterprise versions the feature was promoted from experimental to non-experimental.
The challenge here is that OSS and Enterprise are (still) **documented together**, but they're **not in sync** in promoting the TTL feature: it's still experimental in 5.1 (released) but no longer experimental in 2022.2 (to be released soon).
We can take one of the following approaches:
a) Merge this PR with master and ask the 2022.2 users to refer to master.
b) Merge this PR with master and then backport to branch-5.1. If we choose this approach, it is necessary to backport https://github.com/scylladb/scylladb/pull/11997 beforehand to avoid conflicts.
I'd opt for a) because it makes more sense from the OSS perspective and helps us avoid mess and backporting.
Closes#12295
* github.com:scylladb/scylladb:
doc: fix the version in the comment on removing the note
doc: specify the versions where Alternator TTL is no longer experimental