fix(140): addition more explanation for cases

Clarifying the importance of the usage of uniform
lower_snake_case across json and grpc

Author: toumorokoshi

aep/general/0140/aep.md.j2

@@ -44,6 +44,10 @@ generated code.
     transformed by substituting hyphens (`-`) for underscores (`_`), emitted in
     lowercase, and parsed case-insensitively.
 
+Although gRPC-json transcoding often translates snake_case names to camelCase,
+this variance can force additional complexity server-side to translate the
+values in contexts such as in filter syntax.
+
 #### Support for lowerCamelCase in clients
 
 [ProtoJSON][proto-json] and [gRPC-Gateway][grpc-gateway] by default both

aep/general/0155/aep.md.j2

@@ -48,13 +48,10 @@ message CreateBookRequest {
 
 - [`aep.api.IdempotencyKey`][IdempotencyKey] has a `key` and a `first_sent`
   timestamp.
-
   - `key` is simply a unique identifier.
 
 - Providing an idempotency key **must** guarantee idempotency.
-
   - If a duplicate request is detected, the server **must** return one of:
-
     - A response equivalent to the response for the previously successful
       request, because the client most likely did not receive the previous
       response.
@@ -75,7 +72,6 @@ message CreateBookRequest {
 
 - The `idempotency_key` field **must** be provided on the request message to
   which it applies (and it **must not** be a field on resources themselves).
-
   - The `first_sent` field can be used by API servers to determine if a key is
     expired. API servers **must** reject requests with expired keys, and
     **must** reject requests with keys that are in the future. When feasible,