Merge bitcoin/bitcoin#32134: descriptors: Multipath/PR 22838 follow-ups

56f271e9b9 descriptors refactor: Clarify multipath data relationships through local struct (Hodlinator)
7e974f474e descriptors refactor: Use range-for and limit scope of seen_multipath (Hodlinator)
99a92efdd9 descriptors doc: Correct Markdown format + wording (Hodlinator)

Pull request description:

  Follows up on unresolved suggestions from #22838. In order of priority:

  1. Fixes a couple of typos [^1][^2] and indentation to conform to Markdown.
  2. Solves `for`-loop nit [^3] and also limits variable scope.
  3. Clarifies data relationships [^4][^5] by introducing `struct` rather than comments.

  [^1]: https://github.com/bitcoin/bitcoin/pull/22838#discussion_r1713711352
  [^2]: https://github.com/bitcoin/bitcoin/pull/22838#discussion_r1735039600
  [^3]: https://github.com/bitcoin/bitcoin/pull/22838#discussion_r1735041704
  [^4]: https://github.com/bitcoin/bitcoin/pull/22838#discussion_r1715150336
  [^5]: https://github.com/bitcoin/bitcoin/pull/22838#discussion_r1715151078

ACKs for top commit:
  Prabhat1308:
    re-ACK [`56f271e`](56f271e9b9)
  mabu44:
    tACK 56f271e9b9
  l0rinc:
    utACK 56f271e9b9
  rkrux:
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Tree-SHA512: 75777c911640038a3e0ea48601c0f55463a5f8ff5b3462d81e8992d9fc8f988d5a240e2166befa67a2a246696b0863f8e2508524c14697c490d3b229fe048996

doc/descriptors.md

@@ -288,11 +288,11 @@ For example, a descriptor of the form:
 
     multi(2,xpub.../<0;1;2>/0/*,xpub.../<2;3;4>/*)
 
-will expand to the two descriptors
+will expand to the 3 descriptors
 
-   multi(2,xpub.../0/0/*,xpub.../2/*)
-   multi(2,xpub.../1/0/*,xpub.../3/*)
-   multi(2,xpub.../2/0/*,xpub.../4*)
+    multi(2,xpub.../0/0/*,xpub.../2/*)
+    multi(2,xpub.../1/0/*,xpub.../3/*)
+    multi(2,xpub.../2/0/*,xpub.../4/*)
 
 When this tuple contains only two elements, wallet implementations can use the
 first descriptor for receiving addresses and the second descriptor for change addresses.