bad links in taproot asset channel RPC docs

[ZZiigguurraatt]

In the Taproot Asset Channels docs, we have a number of links that don't work to objects that are inherited from LND. For example:

• https://lightning.engineering/api-docs/api/taproot-assets/taproot-asset-channels/add-invoice/
  • Invoice should link to https://lightning.engineering/api-docs/api/lnd/lightning/add-invoice/#lnrpcinvoice
  • AddInvoiceResponse should link to https://lightning.engineering/api-docs/api/lnd/lightning/add-invoice/#lnrpcaddinvoiceresponse
• https://lightning.engineering/api-docs/api/taproot-assets/taproot-asset-channels/decode-asset-pay-req/
  • PayReq should link to ????
• https://lightning.engineering/api-docs/api/taproot-assets/taproot-asset-channels/send-payment/
  • SendPaymentRequest should link to https://lightning.engineering/api-docs/api/lnd/router/send-payment-v2/#routerrpcsendpaymentrequest
  • Payment should link to https://lightning.engineering/api-docs/api/lnd/router/send-payment-v2/#lnrpcpayment

It is super confusing to new users who don't know these are actually inherited from LND and for people who already know it, it's annoying to have to manually go to the relevant LND RPC doc to read about the object's definition.