docs: Describe patch files

Provide rationale for patch-package modifications.

patches/README.md

@@ -24,8 +24,16 @@ See https://github.com/facebook/react/pull/17883.
 
 ### `patches/react-devtools-core+4.28.5.patch`
 
-No notes.
+The mobile editor relies upon `jsdom-jscore-rn` to create a partial DOM
+environment, which causes `react-devtools-core` to believe it's running in a
+browser environment. We added a custom conditional to disable browser-specific
+features when running in a `jsdom-jscore-rn` environment.
+
+See https://github.com/WordPress/gutenberg/pull/47616.
 
 ### `patches/react-native+0.73.3.patch`
 
-No notes.
+Accessibility changes in React Native 0.73.0 resulted in a broken braille screen
+input on iOS. This patch is a workaround to restore the previous behavior.
+
+See https://github.com/WordPress/gutenberg/pull/53895.