doc: fix typos in secp256k1_ecdsa_{recoverable_,}signature API description #1604

1. 
   theStack commented at 10:11 am on September 9, 2024: contributor

   This small PR fixes two small typos I noticed while looking at the pubkey recovery module (s/structured/structure/).
2. doc: fix typos in `secp256k1_ecdsa_{recoverable_,}signature` API description 292310fbb2
3. real-or-random approved
4. 
   real-or-random commented at 1:23 pm on September 9, 2024: contributor

   utACK 292310fbb24bba324fdf3c47c90e5e576a3cb89d
5. real-or-random added the label user-documentation on Sep 9, 2024
6. real-or-random added the label refactor/smell on Sep 9, 2024
7. real-or-random merged this on Sep 9, 2024
8. real-or-random closed this on Sep 9, 2024

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theStack real-or-random

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user-documentation refactor/smell