docs: mention explicit browser support range (#5354)

* docs: mention explicit browser support range

* fix: pin dates back to 18.0.0

Author: JoshuaKGoldberg

docs-next/src/content/docs/running/browsers.mdx

@@ -37,6 +37,14 @@ A typical setup might look something like the following, where we call `mocha.se
 </html>
 ```
 
+Mocha supports the latest major versions of evergreen browsers available when Mocha's oldest supported Node.js major version was released.
+As of Mocha v11.0.0, that includes the following browser versions that were stable as of [Node.js 18.10.0](https://nodejs.org/en/blog/release/v18.0.0)'s release on April 19, 2022:
+
+- [Chrome 100](https://developer.chrome.com/blog/new-in-chrome-100)
+- [Edge 100](https://learn.microsoft.com/en-us/deployedge/microsoft-edge-relnote-archive-stable-channel#version-1000118544-april-15)
+- [Firefox 99](https://www.mozilla.org/en-US/firefox/99.0/releasenotes)
+- [Safari 15.4](https://developer.apple.com/documentation/safari-release-notes/safari-15_4-release-notes)
+
 ## Grep
 
 The browser may use the `--grep` as functionality.

docs/index.md

@@ -2158,6 +2158,14 @@ A typical setup might look something like the following, where we call `mocha.se
 </html>
 ```
 
+Mocha supports the latest major versions of evergreen browsers available when Mocha's oldest supported Node.js major version was released.
+As of Mocha v11.0.0, that includes the following browser versions that were stable as of [Node.js 18.10.0](https://nodejs.org/en/blog/release/v18.0.0)'s release on April 19, 2022:
+
+- [Chrome 100](https://developer.chrome.com/blog/new-in-chrome-100)
+- [Edge 100](https://learn.microsoft.com/en-us/deployedge/microsoft-edge-relnote-archive-stable-channel#version-1000118544-april-15)
+- [Firefox 99](https://www.mozilla.org/en-US/firefox/99.0/releasenotes)
+- [Safari 15.4](https://developer.apple.com/documentation/safari-release-notes/safari-15_4-release-notes)
+
 ### Grep
 
 The browser may use the `--grep` as functionality. Append a query-string to your URL: `?grep=api`.