fix(docs): sorting versions in docs header (resolve #660)

docs/_assets/js/versions.js.es6

@@ -1,13 +1,32 @@
 import * as $ from 'jquery'
 
+const sortVersions = arr =>
+  arr
+    .map(a =>
+      a
+        .split('.')
+        .map(n => (isNaN(n) ? n : +n + 100000))
+        .join('.')
+    )
+    .sort()
+    .map(a =>
+      a
+        .split('.')
+        .map(n => (isNaN(n) ? n : +n - 100000))
+        .join('.')
+    )
+
 function update() {
   jQuery.getJSON('https://s3.amazonaws.com/botpress-docs/versions.json', function(data) {
-    $('#dropdownVersion + .dropdown-menu').empty()
     const current = $('.navbar-versions-label').text()
-    data.sort().reverse().forEach(version => {
-      const activeCls = current === version ? ' active' : ''
-      $('#dropdownVersion + .dropdown-menu').append(`<a href="/docs/${version}" class="dropdown-item ${activeCls}">${version}</a>`)
-    })
+    $('#dropdownVersion + .dropdown-menu').html(
+      sortVersions(data)
+        .reverse()
+        .map(version => {
+          const activeCls = current === version ? ' active' : ''
+          return `<a href="/docs/${version}" class="dropdown-item ${activeCls}">${version}</a>`
+        })
+    )
   })
 }