Rancher rke/rke2 updates and adding k3s distro column

Contains:

• several updates to Rancher RKE (now)/RKE2 (Q3) column, containing updated rke information as well as information about rke2
• adding populated column for k3s distro with first pass at support levels/capabilities
• updating cure53 pentest report link (see #2 (closed))
• updating overall table formatting to prettyprinted markdown view to support easier editing/conversions for all vendors
  • note: no contents outside the Rancher RKE (now)/RKE2 (Q3) and Rancher k3s columns were intentionally modified during this process, if such edits are made this is a mistake. Please let me know if any are found and I'll address them asap.