add CI check for options documentation (#4804)

* add CI check for options documentation

Ensure that documented options reflect available beacon node options.

* escape `\`

* use bash

* override `COLUMNS` for extracting help text

ci/Jenkinsfile

@@ -60,6 +60,16 @@ pipeline {
     stage('Build') {
       steps { timeout(40) {
         sh 'make LOG_LEVEL=TRACE'
+        /* Check documentation reflects `nimbus_beacon_node --help`. */
+        sh '''#!/usr/bin/env bash
+          diff -u \\
+            <(sed -n '/Usage/,/^...$/ { /^...$/d; p; }' \\
+              docs/the_nimbus_book/src/options.md) \\
+            <(COLUMNS=200 build/nimbus_beacon_node --help | \\
+              sed -n '/Usage/,/Available sub-commands/ { /Available sub-commands/d; p; }' | \\
+              sed 's/\\x1B\\[[0-9;]*[mG]//g' | \\
+              sed 's/[[:space:]]*$//')
+        '''
       } }
     }