docs: block outdated docs from indexing (#8048)

we want only latest to be indexed, so we added robots.txt to help us
with that

Author: patrycjakalinska

packages/docs-reanimated/static/robots.txt

@@ -0,0 +1,5 @@
+User-agent: *
+Disallow: /react-native-reanimated/docs/1.x/
+Disallow: /react-native-reanimated/docs/2.x/
+Disallow: /react-native-reanimated/docs/3.x/
+Allow: /react-native-reanimated/docs/