Adds query param for version no

This adds support for using a query parameter for selecting the version no

Author: aszenz

docs/index.html

@@ -79,6 +79,8 @@
         <script>
             const RusfmtTagsUrl = 'https://api.github.com/repos/rust-lang/rustfmt/tags';
             const UrlHash = window.location.hash.replace(/^#/, '');
+            const queryParams = new URLSearchParams(window.location.search);
+            const versionNumber = null !== queryParams.get('version') ? 'v' + queryParams.get('version') : 'master';
             new Vue({
               el: '#app',
               data: {
@@ -87,7 +89,7 @@
                 configurationDescriptions: [],
                 searchCondition: UrlHash,
                 shouldStable: false,
-                version: 'master',
+                version: versionNumber,
                 oldVersion: undefined,
                 versionOptions: ['master']
               },