feat: improve api doc code to fix / add more coverage

[arlyon]

Summary

Improves the url finding code in the codegen such that we cover more of the (and fix broken) urls. Closes #326.

Checklist

• ran cargo make fmt
• using conventional commits to hightlight user-facing fixes and features

[codecov]

Codecov Report

Merging #332 (fecaa2e) into master (ae86ff4) will increase coverage by 1.04%.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##           master    #332      +/-   ##
=========================================
+ Coverage    5.53%   6.57%   +1.04%     
=========================================
  Files         147     130      -17     
  Lines       14713   20022    +5309     
=========================================
+ Hits          814    1317     +503     
- Misses      13899   18705    +4806     

Impacted Files	Coverage Δ
src/resources/generated/balance.rs	0.00% <0.00%> (ø)
src/resources/generated/cash_balance.rs	0.00% <ø> (ø)
src/resources/generated/checkout_session.rs	0.00% <ø> (ø)
src/resources/generated/issuing_authorization.rs	0.00% <ø> (ø)
src/resources/generated/issuing_card.rs	0.00% <ø> (ø)
src/resources/generated/issuing_cardholder.rs	0.00% <ø> (ø)
src/resources/generated/issuing_dispute.rs	0.00% <ø> (ø)
src/resources/generated/issuing_transaction.rs	0.00% <ø> (ø)
src/resources/generated/login_link.rs	0.00% <ø> (ø)
src/resources/generated/payment_link.rs	0.00% <ø> (ø)
... and 167 more

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