docs(readme): update requirements to mention M1-based macs

README.md

@@ -66,7 +66,7 @@
 
 ## System Requirements
 
-- Intel-based Mac running macOS 10.15.x or later.
+- macOS 10.15.x or later (uses Rosetta2 on M1-based macs).
 - Homebrew `gcc` formula (nightly builds only).
 - Xcode Command Line Tools (nightly builds only).
 
@@ -88,7 +88,9 @@ any issues.
 
 ### Homebrew Cask
 
-1. Install the `jimeh/emacs-builds` Homebrew tap:
+1. Install the
+   [`jimeh/emacs-builds`](https://github.com/jimeh/homebrew-emacs-builds)
+   Homebrew tap:
    ```
    brew tap jimeh/emacs-builds
    ```