[documentation] Please clarify/amend release notes w.r.t. future release schedule for v9/v10

[m-ueberall]

According to the minutes of the last Gluster Community Meeting on 08/03/2022,

• [Saju] Release updates
  • 9.x will receive updates once in 6 month
  • 10.x will receive update once in 3 month

Please clarify whether this will already affect maintenance releases 9.6 and 10.2 (and in that case modify RN 9.5 and RN 10.1).