C2MS11 — Rework some text for Archive Message Retrieval Request

After discussion in the C2MS 1.1 RTF March, 2024, we decided to soften some of the language that was previously inserted as part of the C2MS11-43 resolution, since the shorthand method, though deprecated, is still allowed.

Do this in 1.1

This issue shows changes to the already-approved text from the resolution for C2MS11-43, with the intent being to allow for use of the now-deprecated REQ-STRING if desired.

The text here uses the C2MS11-43 text as a basis, with additions and subtractions shown to it as normal.