Update old versions' syntax
diff --git a/versions/v0_9_0/mkdocs.yml b/versions/v0_9_0/mkdocs.yml
index 4e5f136..15d2fc5 100644
--- a/versions/v0_9_0/mkdocs.yml
+++ b/versions/v0_9_0/mkdocs.yml
@@ -1,9 +1,11 @@
 site_name: Apache Mynewt
 site_url: http://mynewt.apache.org
 
-theme_dir: 'custom-theme'
+theme:
+    name: null
+    custom_dir: "custom-theme"
 
-pages:
+nav:
 - Home: 'index.md'
 - Quick Start: 'quick-start.md'
 - About: 'about.md'
diff --git a/versions/v1_0_0/mkdocs.yml b/versions/v1_0_0/mkdocs.yml
index f363639..c79c571 100644
--- a/versions/v1_0_0/mkdocs.yml
+++ b/versions/v1_0_0/mkdocs.yml
@@ -1,9 +1,11 @@
 site_name: Apache Mynewt
 site_url: http://mynewt.apache.org
 
-theme_dir: 'custom-theme'
+theme:
+    name: null
+    custom_dir: "custom-theme"
 
-pages:
+nav:
 - Home: 'index.md'
 - Pages:
     - Bluetooth Low Energy 4.2: 'pages/ble.md'
diff --git a/versions/v1_1_0/mkdocs.yml b/versions/v1_1_0/mkdocs.yml
index 4f5f646..5d0d6ce 100644
--- a/versions/v1_1_0/mkdocs.yml
+++ b/versions/v1_1_0/mkdocs.yml
@@ -3,9 +3,11 @@
 repo_url: https://github.com/apache/mynewt-site/
 edit_uri: blob/master/docs
 
-theme_dir: 'custom-theme'
+theme:
+    name: null
+    custom_dir: "custom-theme"
 
-pages:
+nav:
 - Home: 'index.md'
 - Pages:
     - Bluetooth Low Energy 4.2: 'pages/ble.md'
diff --git a/versions/v1_2_0/mkdocs.yml b/versions/v1_2_0/mkdocs.yml
index 8d21f0c..0fdccf3 100644
--- a/versions/v1_2_0/mkdocs.yml
+++ b/versions/v1_2_0/mkdocs.yml
@@ -3,9 +3,11 @@
 repo_url: https://github.com/apache/mynewt-site/
 edit_uri: blob/master/docs
 
-theme_dir: 'custom-theme'
+theme:
+    name: null
+    custom_dir: "custom-theme"
 
-pages:
+nav:
 - Home: 'index.md'
 - Pages:
     - Bluetooth Low Energy 4.2: 'pages/ble.md'
diff --git a/versions/v1_3_0/mkdocs.yml b/versions/v1_3_0/mkdocs.yml
index 4c8a528..a9a1ab3 100644
--- a/versions/v1_3_0/mkdocs.yml
+++ b/versions/v1_3_0/mkdocs.yml
@@ -2,11 +2,12 @@
 site_url: http://mynewt.apache.org
 repo_url: https://github.com/apache/mynewt-site/
 edit_uri: blob/master/docs
-site_favicon: /img/mynewt-logo-only-newt32x32.png
 
-theme_dir: 'custom-theme'
+theme:
+    name: null
+    custom_dir: "custom-theme"
 
-pages:
+nav:
 - Home: 'index.md'
 - Pages:
     - Bluetooth Low Energy 4.2: 'pages/ble.md'