Update build concurrency numbers for Business
This matches them with reality :)
@@ -23,7 +23,7 @@ Our current build limits are:
* 30 minutes build time
* 7GB of memory
- * 4 concurrent builds
+ * Concurrent builds vary based on your pricing plan
If you are having trouble with your documentation builds,
you can reach our support at support@readthedocs.com.
