Merge bitcoindevkit/bdk#703: Fix minor typos in docs

134b19a9cb127989402fe331f48a1e37eb3cdcad Fix minor typos in docs (thunderbiscuit)

Pull request description:

  ### Description
  This PR fixes:
  1. The use of "i.e." in docs, sometimes spelled as "ie."
  2. A small typo in the sentence "Note that this methods only operate on the internal database..."
  3. A small typo in the sentence "Finish the building the transaction"

  I came across these while building docs for bdk-kotlin.

  ### Notes to the reviewers

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  danielabrozzoni:
    ACK 134b19a9cb127989402fe331f48a1e37eb3cdcad

Tree-SHA512: 67296999eba8ffe1fe64756fa023d85064774cb9d4c26e99054d467b5024baea4138f11d602d04e695412c61625ee4f5b4687b75f177cfec2604a6c61a5a6216