Explain in docs that v3 is closed off to new features

Refs #18112
[skip sauce]

1 files changed, 4 insertions, 0 deletions

diff --git a/README.md b/README.md
index 5785e92239..79ff31c093 100644
--- a/README.md
+++ b/README.md
@@ -71,6 +71,8 @@ We provide compiled CSS and JS (`bootstrap.*`), as well as compiled and minified
 
 Have a bug or a feature request? Please first read the [issue guidelines](https://github.com/twbs/bootstrap/blob/master/CONTRIBUTING.md#using-the-issue-tracker) and search for existing and closed issues. If your problem or idea is not addressed yet, [please open a new issue](https://github.com/twbs/bootstrap/issues/new).
 
+Note that **feature requests must target [Bootstrap v4](https://github.com/twbs/bootstrap/tree/v4-dev),** because Bootstrap v3 is now in maintenance mode and is closed off to new features. This is so that we can focus our efforts on Bootstrap v4.
+
 
 ## Documentation
 
@@ -99,6 +101,8 @@ Please read through our [contributing guidelines](https://github.com/twbs/bootst
 
 Moreover, if your pull request contains JavaScript patches or features, you must include [relevant unit tests](https://github.com/twbs/bootstrap/tree/master/js/tests). All HTML and CSS should conform to the [Code Guide](https://github.com/mdo/code-guide), maintained by [Mark Otto](https://github.com/mdo).
 
+**Bootstrap v3 is now closed off to new features.** It has gone into maintenance mode so that we can focus our efforts on [Bootstrap v4](https://github.com/twbs/bootstrap/tree/v4-dev), the future of the framework. Pull requests which add new features (rather than fix bugs) should target [Bootstrap v4 (the `v4-dev` git branch)](https://github.com/twbs/bootstrap/tree/v4-dev) instead.
+
 Editor preferences are available in the [editor config](https://github.com/twbs/bootstrap/blob/master/.editorconfig) for easy use in common text editors. Read more and download plugins at <http://editorconfig.org>.