Restructure documentation

Change-Id: I2640e68972cb7c5ed67032a3b575a2aec056f592
diff --git a/.gitignore b/.gitignore
index f51ef92..9df09e9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@
 .RData
 .Ruserdata
 cache/
+docs