Add mass revocation readiness language (#273)

Fixes #272

Author: aarongable

CP-CPS.md

@@ -782,6 +782,8 @@ See [Section 6.1](#61-key-pair-generation-and-installation).
 
 ISRG has created and maintains incident response procedures for a range of potential compromise and disaster situations. Such situations include, but are not limited to, natural disasters, security incidents, and equipment failure. Incident response plans are reviewed, potentially updated, and tested on at least an annual basis.
 
+ISRG maintains a comprehensive and actionable plan for mass revocation events, performs annual testing of this procedure, and incorporates lessons learned to improve preparedness over time.
+
 ### 5.7.2 Computing resources, software, and/or data are corrupted
 
 In the event that computing resources, software, and/or data are corrupted or otherwise damaged, ISRG will assess the situation, including its impact on CA integrity and security, and take appropriate action. CA operations may be suspended until mitigation is complete. Subscribers may be notified if corruption or damage has a material impact on the service provided to them.