Update branch based context to production

This removes the branch based context of "context.main" which would be triggered
and override any other contexts even during the PR cycle. The assumption here is
that "production" context is marked appropriately on Netlify admin UI, and once
it's in place, this should have the same effect to ensure we do not publish any
draft or future date posts.

Author: rytswd

netlify.toml

@@ -21,8 +21,10 @@ command = "git submodule update --init --recursive --depth 1 && make deploy-prev
 [context.branch-deploy]
 command = "git submodule update --init --recursive --depth 1 && make non-production-build && npx -y pagefind --site public"
 
-[context.main]
-# This context is triggered by the `main` branch and allows search indexing
-# DO NOT REMOVE THIS (contact @kubernetes/sig-docs-leads)
+[context.production]
+# Rather than specifying context.main, which will supersede any of the above
+# context, make a production specific build separately based on the context
+# with the same priority.
+# Ref: https://docs.netlify.com/configure-builds/file-based-configuration/#deploy-contexts
 publish = "public"
 command = "git submodule update --init --recursive --depth 1 && make production-build && npx -y pagefind --site public"