codegen: Opt out of documentation (#843)

* codegen: Opt-out for API documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* cli: Add `--no-docs` flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Check no documentation was generated

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update cargo.lock

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Adjust testing for the new codegen API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* macro: Ensure `subxt` macro does not contain documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* macro: Expose documentation flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* expose_documentation => generate_docs

---------

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: James Wilson <james@jsdw.me>

codegen/src/api/events.rs

@@ -45,6 +45,7 @@ pub fn generate_events(
     pallet: &PalletMetadata<PortableForm>,
     types_mod_ident: &syn::Ident,
     crate_path: &CratePath,
+    should_gen_docs: bool,
 ) -> TokenStream2 {
     // Early return if the pallet has no events.
     let event = if let Some(ref event) = pallet.event {
@@ -59,6 +60,7 @@ pub fn generate_events(
         |name| name.into(),
         "Event",
         crate_path,
+        should_gen_docs,
     );
     let event_structs = struct_defs.iter().map(|(variant_name, struct_def)| {
         let pallet_name = &pallet.name;
@@ -77,9 +79,12 @@ pub fn generate_events(
     let event_type = type_gen.resolve_type_path(event.ty.id());
     let event_ty = type_gen.resolve_type(event.ty.id());
     let docs = event_ty.docs();
+    let docs = should_gen_docs
+        .then_some(quote! { #( #[doc = #docs ] )* })
+        .unwrap_or_default();
 
     quote! {
-        #( #[doc = #docs ] )*
+        #docs
         pub type Event = #event_type;
         pub mod events {
             use super::#types_mod_ident;