fix(AIP-136): link to AIP-127 for HTTP guidance on body definition. (#1272)

Author: amanda-tarafa

aip/general/0136.md

@@ -58,7 +58,7 @@ services. The bullets below apply in all three cases.
   verb in the name of the RPC.
   - If word separation is required, `camelCase` **must** be used.
 - The `body` clause in the `google.api.http` annotation **should** be `"*"`.
-  - However, if using `GET`, the `body` clause **must** be absent.
+  - See [HTTP and gRPC Transcoding][transcoding] for more information.
 - Custom methods **should** take a request message matching the RPC
   name, with a `Request` suffix.
 - Custom methods **should** return a response message matching the RPC
@@ -163,6 +163,7 @@ without risk of runtime impact.
 [create]: ./0133.md
 [update]: ./0134.md
 [delete]: ./0135.md
+[transcoding]: ./0127.md
 
 ### RPC name
 
@@ -176,6 +177,7 @@ languages.
 
 ## Changelog
 
+- **2023-11-16:** Included link to AIP-127 "HTTP and gRPC Transcoding" for guidance on body definition.
 - **2023-05-16:** Added prohibition of the term "async" within RPC names.
 - **2023-05-09:** Adding guidance for POST and GET, require parent instead of
   the resource singular.