fix(dev): rename superBlock with v7 to certSlug (#41738)

* fix(dev): rename superBlock with v7 to slug

* improve name slug -> certSlug

* superBlockTitle -> superBlock

* correct teeny, tiny mistake

* fix: correct slug to certSlug in certLocation

* refactor currentCerts

* rename showCert cert -> certSlug and various

client/gatsby-node.js

@@ -132,6 +132,7 @@ exports.createPages = function createPages({ graphql, actions, reporter }) {
         );
 
         // Create intro pages
+        // TODO: Remove allMarkdownRemark (populate from elsewhere)
         result.data.allMarkdownRemark.edges.forEach(edge => {
           const {
             node: { frontmatter, fields }