Handbook documentation & build flow fixes

build.gradle

@@ -386,6 +386,12 @@ tasks.register('generateHandbook') {
             return
         }
 
+        // Install dependencies before building.
+        exec {
+            workingDir 'src/handbook'
+            commandLine npm, 'install'
+        }
+
         // Build the handbook.
         exec {
             workingDir 'src/handbook'