docs: move breaking changes out of API folder (#21870)

This should allow planned breaking changes to be shown in the website
prior to a stable release with the changes included.

docs/README.md

@@ -112,7 +112,7 @@ These individual tutorials expand on topics discussed in the guide above.
 * [Process Object](api/process.md)
 * [Supported Command Line Switches](api/command-line-switches.md)
 * [Environment Variables](api/environment-variables.md)
-* [Breaking API Changes](api/breaking-changes.md)
+* [Breaking API Changes](breaking-changes.md)
 
 ### Custom DOM Elements:
 

docs/api/breaking-changes.md → docs/breaking-changes.md

 # Breaking Changes
 
-Breaking changes will be documented here, and deprecation warnings added to JS code where possible, at least [one major version](../tutorial/electron-versioning.md#semver) before the change is made.
+Breaking changes will be documented here, and deprecation warnings added to JS code where possible, at least [one major version](tutorial/electron-versioning.md#semver) before the change is made.
 
 ## `FIXME` comments
 

docs/tutorial/support.md

@@ -108,4 +108,4 @@ are also verified to be able to run the prebuilt binaries of Electron:
 * Fedora 21
 * Debian 8
 
-[arm-breaking-change]: https://github.com/electron/electron/blob/master/docs/api/breaking-changes.md#duplicate-arm-assets
+[arm-breaking-change]: ../breaking-changes.md#duplicate-arm-assets

filenames.auto.gni

@@ -4,8 +4,6 @@ auto_filenames = {
     "docs/api/accelerator.md",
     "docs/api/app.md",
     "docs/api/auto-updater.md",
-    "docs/api/breaking-changes-ns.md",
-    "docs/api/breaking-changes.md",
     "docs/api/browser-view.md",
     "docs/api/browser-window-proxy.md",
     "docs/api/browser-window.md",