re-enable percy checks on PRs

.env.example

@@ -1,18 +1,21 @@
-FAUNADB_ADMIN_SECRET=
+# Production:
+
+AIRTABLE_API_KEY=
+AIRTABLE_BASE=
 FAUNADB_SERVER_SECRET=
 GH_PUBLIC_TOKEN=
+HCAPTCHA_SITE_KEY=
+HCAPTCHA_SECRET_KEY=
+SENTRY_DSN=
 SPOTIFY_REFRESH_TOKEN=
 SPOTIFY_CLIENT_SECRET=
 SPOTIFY_CLIENT_ID=
-WEBMENTIONS_TOKEN=
-PERCY_TOKEN=
-LHCI_SERVER_BASE_URL=
-LHCI_TOKEN=
+
+# CI:
+
 LHCI_ADMIN_TOKEN=
 LHCI_GITHUB_APP_TOKEN=
+LHCI_TOKEN=
 SENTRY_AUTH_TOKEN=
-SENTRY_DSN=
-AIRTABLE_API_KEY=
-AIRTABLE_BASE=
-HCAPTCHA_SITE_KEY=
-HCAPTCHA_SECRET_KEY=
+PERCY_TOKEN=
+WEBMENTIONS_TOKEN=