adjust headings in README

Author: ndbroadbent

README.md

@@ -52,7 +52,7 @@ outputs:
 
 Run it with `bundle exec sorbet-typescript export --config sorbet_typescript.yml`. Any CLI options override the config file.
 
-#### What gets generated?
+## What gets generated?
 
 Each output captures the same Sorbet definitions in a format that is convenient for different consumers:
 
@@ -62,7 +62,7 @@ Each output captures the same Sorbet definitions in a format that is convenient
 
 These files share the same structure whether you call the CLI or the Ruby API, making it easy to feed the JSON into documentation generators, schemas, or client SDKs.
 
-### Ruby API
+## Ruby API
 
 If you want to script the export yourself, use the `Exporter` directly: