devtools/hackdoc: init

This is hackdoc, a documentation rendering tool for monorepos.

This is the first code iteration, that can only serve from a local git
checkout.

The code is incomplete, and is WIP.

Change-Id: I68ef7a991191c1bb1b0fdd2a8d8353aba642e28f
diff --git a/devtools/hackdoc/source/source.go b/devtools/hackdoc/source/source.go
new file mode 100644
index 0000000..a79a920
--- /dev/null
+++ b/devtools/hackdoc/source/source.go
@@ -0,0 +1,10 @@
+package source
+
+type Source interface {
+	IsFile(path string) (bool, error)
+	ReadFile(path string) ([]byte, error)
+	IsDirectory(path string) (bool, error)
+
+	CacheSet(dependencies []string, key string, value interface{})
+	CacheGet(key string) interface{}
+}