docs: add developing section and move building docs there (#456)

website/content/docs/developing/building.mdx

@@ -7,7 +7,7 @@ description: Building Boundary
 
 # Building Boundary
 
-Building Boundary from source has a few requirements:
+Building Boundary from source requires:
 
 - [Golang](https://golang.org/dl/) 1.15 or greater
 - `make` installed

website/content/docs/developing/index.mdx

@@ -0,0 +1,10 @@
+---
+layout: docs
+page_title: Documentation
+sidebar_title: Developing Boundary
+description: Developing Boundary
+---
+
+# Developing Boundary
+
+Please consult our [project on GitHub](https://github.com/hashicorp/boundary) for more information about contributing and developing Boundary.

website/data/docs-navigation.js

@@ -9,12 +9,16 @@
 export default [
   {
     category: 'getting-started',
-    content: ['building', 'run-and-login', 'connect-to-target'],
+    content: ['run-and-login', 'connect-to-target'],
   },
   {
     category: 'installing',
     content: ['production'],
   },
+  {
+    category: 'developing',
+    content: ['building'],
+  },
   {
     category: 'concepts',
     content: [