Generated code produces cargo doc warnings

[jdisanti]

Observed in https://github.com/awslabs/aws-sdk-rust/runs/4971673212:

 Documenting aws-sdk-chime v0.6.0 (/home/runner/work/aws-sdk-rust/aws-sdk-rust/sdk/chime)
warning: unresolved link to `self::client::fluent_builders::BatchCreateChannelMembership::r`
   --> src/client.rs:157:47
    |
157 | ...e(ChannelMembershipType)`](crate::client::fluent_builders::BatchCreateChannelMembership::r#type) / [`set_type(Option<ChannelMembership...
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the struct `BatchCreateChannelMembership` has no field or associated item named `r`
    |
    = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default

warning: unresolved link to `self::client::fluent_builders::CreateChannelMembership::r`
   --> src/client.rs:345:47
    |
345 | ...ype(ChannelMembershipType)`](crate::client::fluent_builders::CreateChannelMembership::r#type) / [`set_type(Option<ChannelMembershipTyp...
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the struct `CreateChannelMembership` has no field or associated item named `r`

warning: unresolved link to `self::client::fluent_builders::ListChannelMemberships::r`
    --> src/client.rs:1530:47
     |
1530 | ...ype(ChannelMembershipType)`](crate::client::fluent_builders::ListChannelMemberships::r#type) / [`set_type(Option<ChannelMembershipType...
     |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the struct `ListChannelMemberships` has no field or associated item named `r`

warning: unresolved link to `self::client::fluent_builders::SendChannelMessage::r`
    --> src/client.rs:2112:44
     |
2112 | ...[`r#type(ChannelMessageType)`](crate::client::fluent_builders::SendChannelMessage::r#type) / [`set_type(Option<ChannelMessageType>)`](...
     |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the struct `SendChannelMessage` has no field or associated item named `r`

warning: 4 warnings emitted

The r# needs to be omitted for doc links.