Merge bitcoin/bitcoin#22402: doc: Install Rosetta on M1-macOS for qt in depends

cdb41d5 doc: Install Rosetta on M1-macOS for qt in depends (Hennadii Stepanov)

Pull request description:

  On master (c609e10) `make -C depends qt` on Apple Silicon based macOS 11.4 ends with an error:
  ```
  /bin/sh: /Users/hebasto/bitcoin/depends/work/build/aarch64-apple-darwin20.5.0/qt/5.12.11-6c4d47a8f8f/qtbase/bin/moc: Bad CPU type in executable
  ```

  Installing Rosetta 2 fixes it.

  Explanation. On Apple Silicon macOS the `qt` package in depends actually is cross compiled. All native tools (including `moc`) are x86_64 binaries, that require Rosetta 2 to run.

ACKs for top commit:
  promag:
    ACK cdb41d5.
  fanquake:
    ACK cdb41d5 - I have not tested after installing Rosetta 2, but I saw the same issue during my first cross-compile on an M1 box.
  Zero-1729:
    ACK cdb41d5

Tree-SHA512: fb06a32d6fb40f405ce856b44f5d3af0c51089886f3be79e509e5c325614d7af58ce4480c064c17e0efb695a1f69f68d533c417f9631d46d8a630aba60ce4433

Author: fanquake

depends/README.md

@@ -87,6 +87,14 @@ For linux S390X cross compilation:
 
     sudo apt-get install g++-s390x-linux-gnu binutils-s390x-linux-gnu
 
+### Install the required dependencies: M1-based macOS
+
+To be able to build the `qt` package, ensure that Rosetta 2 is installed:
+
+```
+softwareupdate --install-rosetta
+```
+
 ### Dependency Options
 
 The following can be set when running make: `make FOO=bar`