move layout setting to 11data file

src/about.njk

@@ -1,5 +1,4 @@
 ---
-layout: base.njk
 title: About the Classifieds
 ---
 

src/index.njk

@@ -1,5 +1,4 @@
 ---
-layout: base.njk
 title: Fediverse Skillshare Classifieds
 ---
 {% css %}{% include "css/listings.css" %}{% endcss %}

src/src.11tydata.js

@@ -0,0 +1,3 @@
+export default {
+  layout: "base.njk"
+}

src/submit.njk

@@ -1,5 +1,4 @@
 ---
-layout: base.njk
 title: Submit a Listing
 ---