Merge bitcoin/bitcoin#26093: doc: consolidate release-note fragments pre-wiki

b0349a7 doc: consolidate & remove release-note fragments (fanquake)

Pull request description:

  The formatting / ordering doesn't matter a great deal here, given this will shortly be moving to the wiki for further additions / formatting changes etc.

ACKs for top commit:
  MarcoFalke:
    ACK b0349a7
  achow101:
    ACK b0349a7
  jarolrod:
    ACK b0349a7

Tree-SHA512: 80d2f9f25bc13d407ab9fd0473ff02043a1e6b9895e27d3229d717d357606063472582d31bc1b4058741d2e34be806ef1460acd66d43d6493562ffcf3f6defa5

Author: MacroFake

doc/README.md

@@ -53,7 +53,6 @@ The Bitcoin repo's [root README](/README.md) contains relevant information on th
 
 - [Developer Notes](developer-notes.md)
 - [Productivity Notes](productivity.md)
-- [Release Notes](release-notes.md)
 - [Release Process](release-process.md)
 - [Source Code Documentation (External Link)](https://doxygen.bitcoincore.org/)
 - [Translation Process](translation_process.md)