build: add Node 16 and 18 to the CI matrix

Update documentation, so that it does not become outdated whenever a new version of Node is released.

Test on the current version of Node, so we can spot problems early, but don't claim to support it as current release line sometimes introduces bugs, which are later fixed by Node itself.

Fixes karma-runner#3728

.github/workflows/test.yml

@@ -20,7 +20,7 @@ jobs:
           fetch-depth: 0
       - uses: actions/setup-node@v2
         with:
-          node-version: 14
+          node-version: 16
           cache: npm
       - run: npm ci
       - run: npm run build:check
@@ -33,7 +33,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [10, 12]
+        node: [10, 12, 14, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
@@ -48,7 +48,7 @@ jobs:
     runs-on: windows-latest
     strategy:
       matrix:
-        node: [10, 12, 14]
+        node: [10, 12, 14, 16, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2

docs/intro/01-installation.md

@@ -5,7 +5,7 @@ Karma runs on [Node.js] and is available as an [npm] package.
 On Mac or Linux we recommend using [NVM](https://github.com/creationix/nvm). On Windows, download Node.js
 from [the official site](https://nodejs.org/) or use the [NVM PowerShell Module](https://www.powershellgallery.com/packages/nvm).
 
-Note: Karma currently works on Node.js **6.x**, **8.x**, and **10.x**. See [FAQ] for more info.
+Karma works on all [LTS releases](https://nodejs.org/en/about/releases/) of Node.js.
 
 ## Installing Karma and plugins
 

docs/intro/04-faq.md

@@ -27,7 +27,7 @@ The latest stable version from npm (`npm install karma`). See [versioning] for m
 
 
 ### Which version of Node.js does Karma run with?
-Karma works on all active LTS versions of node as specified by the [Node.js Release Working Group](https://github.com/nodejs/Release/blob/master/README.md). The nodejs version numbers are set in the package.json. Older versions of karma work with older versions of nodejs, but are not maintained or updated.
+Karma works on all LTS versions of Node.js as specified by the [Node.js Release Working Group](https://github.com/nodejs/Release/blob/master/README.md). The Node.js version numbers are set in the package.json. Older versions of karma work with older versions of Node.js, but are not maintained or updated.
 
 [mailing list]: https://groups.google.com/d/forum/karma-users
 [karma-ng-scenario]: https://github.com/karma-runner/karma-ng-scenario