MkDocs hopefully fixed.

mkdocs.yml

@@ -0,0 +1,6 @@
+site_name: TeraHz Documentation
+site_dir: ../site
+nav:
+  - Build guide: 'build.md'
+  - Development-stable dependencies: 'dependencies.md'
+  - Start page: 'index.md'

readthedocs.yml

@@ -0,0 +1,3 @@
+version: 2
+mkdocs:
+  configuration: mkdocs.yml