related topics must all be lowercase

topics/rpc/index.md

@@ -5,6 +5,6 @@ short_description: RPC is a request–response communication protocol.
 topic: rpc
 logo: rpc.png
 wikipedia_url: https://en.wikipedia.org/wiki/Remote_procedure_call
-related: rest-api, graphql-api, soap, wsdl, gRPC
+related: rest-api, graphql-api, soap, wsdl, grpc
 ---
 **Remote procedure call** (**RPC**) is when a computer program causes a procedure to execute in a different address space (commonly on another computer on a shared network), which is coded as if it were a normal (local) procedure call, without the programmer explicitly coding the details for the remote interaction.