go.talks/present: address missed review comments

R=r
CC=golang-dev
https://golang.org/cl/6727047
diff --git a/present/doc.go b/present/doc.go
index 00b3686..76b8497 100644
--- a/present/doc.go
+++ b/present/doc.go
@@ -165,6 +165,7 @@
 The function html includes the contents of the specified file as
 unescaped HTML. This is useful for including custom HTML elements
 that cannot be created using only the slide format.
+It is your responsibilty to make sure the included HTML is valid and safe.
 
 	.html file.html
 
diff --git a/present/parse.go b/present/parse.go
index 327d103..3b037e5 100644
--- a/present/parse.go
+++ b/present/parse.go
@@ -32,6 +32,8 @@
 // Register binds the named action, which does not being with a period, to the
 // specified parser and template function to be invoked when the name, with a
 // period, appears in the slide input text.
+// The function argument is an optional template function that is available
+// inside templates under that name.
 func Register(name string, parser func(fileName string, lineNumber int, inputLine string) (Elem, error), function interface{}) {
 	if len(name) == 0 || name[0] == ';' {
 		panic("bad name in Register: " + name)