doc/tutorial/basics: various improvements

- added section for templates
- updated ambiguity in bottom.md
- several small fixes

Change-Id: Iac03e7b99eec1ea352cb30d815a8cfbfb6896b18
diff --git a/doc/tutorial/basics/fieldcomp.md b/doc/tutorial/basics/fieldcomp.md
index dfb37d8..6723413 100644
--- a/doc/tutorial/basics/fieldcomp.md
+++ b/doc/tutorial/basics/fieldcomp.md
@@ -17,7 +17,7 @@
 
 {
     "\( strings.ToLower(v) )": {
-        pos:     k
+        pos:     k + 1
         name:    v
         nameLen: len(v)
     } for k, v in a