ci(prettier): ignore ADOPTERS.md using .prettierignore

Ignore `ADOPTERS.md` using `.prettierignore`
instead of ignoring it at the GitHub action config.

This will cause the same rules to be applied locally as these checks.

Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>

.github/workflows/ci.yml

@@ -110,7 +110,7 @@ jobs:
         continue-on-error: true
 
       - name: prettier
-        run: yarn prettier:check '!ADOPTERS.md'
+        run: yarn prettier:check
 
       - name: lock
         run: yarn lock:check

.prettierignore

@@ -8,3 +8,6 @@ api-report.md
 plugins/scaffolder-backend/sample-templates
 .vscode
 dist-types
+
+# reduce the barrier for adopters to add themselves
+ADOPTERS.md