Updates kibana MITRE version reference to v13.1 (#3983)

Co-authored-by: Nastasha Solomon <[email protected]>

docs/detections/rules-coverage.asciidoc

@@ -12,7 +12,7 @@ Mirroring the MITRE ATT&CK® framework, columns represent major tactics, and cel
 
 [NOTE]
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-This page only includes the detection rules you currently have installed, and only rules that are mapped to MITRE ATT&CK® tactics. Additionally, rules must be mapped to the MITRE ATT&CK® version used by {elastic-sec}: `v12.1`. Elastic prebuilt rules that aren't installed and custom rules that are either unmapped or mapped to a deprecated tactic or technique will not be included.
+This page only includes the detection rules you currently have installed, and only rules that are mapped to MITRE ATT&CK® tactics. Additionally, rules must be mapped to the MITRE ATT&CK® version used by {elastic-sec}: `v13.1`. Elastic prebuilt rules that aren't installed and custom rules that are either unmapped or mapped to a deprecated tactic or technique will not be included.
 
 You can map custom rules to tactics in **Advanced settings** when creating or editing a rule.
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