Fix comments generated by ShankAccount seeds

[Juici]

Comments were being interpreted as string literals in generated code instead of as comments.

[VincentBerthier]

Hello,
Can we get this merged to fix the seeds problem?

[febo]

@Juici Did you try to use the syntax #[doc = ...] to render the comments? I think this will result in just a couple of files changed.

[Juici]

@Juici Did you try to use the syntax #[doc = ...] to render the comments? I think this will result in just a couple of files changed.

When I wrote the PR I just wanted to do a quick patch with minimal changes. Personally I think an approach using the quote! macro would be cleaner.