update Jenkins CI, add docs build

automation/Dockerfile

@@ -7,5 +7,6 @@ RUN apt-get --yes upgrade
 # tzdata is a dependency, won't install otherwise
 ARG DEBIAN_FRONTEND=noninteractive
 
-RUN rustup target add thumbv6m-none-eabi && \
+RUN rustup install nightly && \
+	rustup target add thumbv6m-none-eabi && \
 	rustup component add rustfmt clippy

automation/Jenkinsfile

@@ -1,47 +1,34 @@
 pipeline {
-    agent any
+    agent {
+        dockerfile {
+            dir 'automation'
+            reuseNode true
+        }
+    }
+
 
     stages {
         stage('Clippy') {
-            agent {
-                dockerfile {
-                    dir 'automation'
-                    reuseNode true
-                }
-            }
             steps {
                 sh 'cargo clippy'
             }
         }
         stage('Rustfmt') {
-            agent {
-                dockerfile {
-                    dir 'automation'
-                    reuseNode true
-                }
-            }
             steps {
                 sh 'cargo fmt'
             }
         }
-        stage('Check') {
-            agent {
-                dockerfile {
-                    dir 'automation'
-                    reuseNode true
-                }
+        stage('Docs') {
+            steps {
+                sh 'cargo +nightly doc'
             }
+        }
+        stage('Check') {
             steps {
                 sh 'cargo check --target thumbv6m-none-eabi'
             }
         }
         stage('Check Examples') {
-            agent {
-                dockerfile {
-                    dir 'automation'
-                    reuseNode true
-                }
-            }
             steps {
                 sh 'cargo check --target thumbv6m-none-eabi --examples'
             }