docs: Add the API spec for Receivers v1beta2

Signed-off-by: Stefan Prodan <[email protected]>

Author: stefanprodan

docs/spec/v1beta2/providers.md

@@ -233,7 +233,7 @@ stringData:
 When set to `true`, the controller will stop sending events to this provider.
 When the field is set to `false` or removed, it will resume.
 
-## Provider guids
+## Provider guides
 
 ### Generic webhook