fix(docs): Fix broken links in tutorial (gatsbyjs#15004)

www/src/data/sidebars/tutorial-links.yaml

@@ -11,10 +11,8 @@
           link: /tutorial/part-zero/#overview-of-core-technologies
         - title: Familiarize with the command line
           link: /tutorial/part-zero/#familiarize-yourself-with-the-command-line
-        - title: Install Node.js
-          link: /tutorial/part-zero/#install-nodejs
-        - title: Familiarize with npm
-          link: /tutorial/part-zero/#familiarize-yourself-with-npm
+        - title: Install Node.js and npm
+          link: /tutorial/part-zero/#-install-nodejs-and-npm
         - title: Install Git
           link: /tutorial/part-zero/#install-git
         - title: Using the Gatsby CLI
@@ -64,7 +62,7 @@
       ui: steps
       items:
         - title: Recap of the first half of the tutorial
-          link: /tutorial/part-four/#recap-of-first-half-of-the-tutorial
+          link: /tutorial/part-four/#recap-of-the-first-half-of-the-tutorial
         - title: Data in Gatsby
           link: /tutorial/part-four/#data-in-gatsby
         - title: How Gatsby uses GraphQL