Fix a policy doc error.

CloudPolicyOverridesPlatformPolicy should be supported since M75 instead
of M65.

Bug: 961432
Change-Id: I3a62576aa8d5c19aced9b339571e53f925078c91
Tbr: pastarmovj
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1601644Reviewed-by: Owen Min <zmin@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Auto-Submit: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658252}

components/policy/resources/policy_templates.json

@@ -12559,7 +12559,7 @@
       'name': 'CloudPolicyOverridesPlatformPolicy',
       'type': 'main',
       'schema': { 'type': 'boolean'},
-      'supported_on': ['chrome.*:65-'],
+      'supported_on': ['chrome.*:75-'],
       'features': {
         'dynamic_refresh': False,
         'per_profile': False,