adjust supported node versions

.github/workflows/ci.yml

@@ -51,7 +51,7 @@ jobs:
     name: Node ${{ matrix.node }}
     strategy:
       matrix:
-        node: [ "12", "14", "16" ]
+        node: [ "14", "16", "18" ]
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2

guide/build.md

@@ -179,7 +179,7 @@ To build the server, you will need the following C libraries installed:
     the `ncurses` library.
 
 To build the UI, you'll need a [nodejs](https://nodejs.org/en/download/) release
-in "Maintenance LTS" or "Active LTS" status: currently v12 or v14.
+in "Maintenance" or "LTS" status: currently v14, v16, or v18.
 
 On recent Ubuntu or Raspbian Linux, the following command will install
 most non-Rust dependencies: