Add note about version to PCW docs

Author: dadlerj

docs/analytics/pcw.mdx

@@ -34,3 +34,5 @@ It’s simple to identify which code is generated by Cody, but much more difficu
 -   We exclude disjoint insertions - insertions made in multiple places at once, which are likely to come from third party sources
 -   We exclude any insertions made in an inactive file/editor window
 -   We exclude any insertions into “stale” code - code the user hasn’t touched in the last 5 seconds
+
+This metric only includes data from users on Cody versions 1.42+.