feat: Added doc comments to Rust reqwest-trait template

[ranger-ross]

This PR is a small QoL improvement to add doc comments to functions based on the endpoint method/path and the operation description.

The format is:

/// {METHOD} {PATH}
/// 
/// {NOTES} 

example:

/// POST /v1/foo
///
/// This creates a foo in the database.

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cc: @frol @farcaller @richardwhiuk @paladinzh @jacob-pro

[ranger-ross]

note: this newline is intentional to give a bit more space between functions to make them easier to read.

[wing328]

@ranger-ross looks good to me. thanks for the contributions as always