Generate a basic documentation website with the mkdocs toolkit.

No content yet other than man pages.  To make the man pages render
nicely in mkdocs, I removed the static %-headers and put the code for
them into default.md.tmp.do instead.  That way, the raw input redo-*.md
files will look right in mkdocs.

Documentation/mkdocs.yml

@@ -0,0 +1,18 @@
+site_name: redo build system
+theme: readthedocs
+docs_dir: .
+site_dir: ../website
+strict: true
+
+pages:
+  - Introduction: index.md
+  - Man Pages:
+    - redo: redo.md
+    - redo-ifchange: redo-ifchange.md
+    - redo-ifcreate: redo-ifcreate.md
+    - redo-always: redo-always.md
+    - redo-stamp: redo-stamp.md
+    - redo-sources: redo-sources.md
+    - redo-targets: redo-targets.md
+    - redo-ood: redo-ood.md
+    - redo-whichdo: redo-whichdo.md