content: revise description of map creation

Change-Id: If81d061de18fd3a8a190c04d3232e8bc247277e8
Reviewed-on: https://go-review.googlesource.com/21449
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Ralph Corderoy <ralph@inputplus.co.uk>
diff --git a/content/moretypes.article b/content/moretypes.article
index e89a962..9cac743 100644
--- a/content/moretypes.article
+++ b/content/moretypes.article
@@ -194,9 +194,11 @@
 
 A map maps keys to values.
 
-Maps must be initialized before use; the `nil` map is empty and cannot be written to.
+The zero value of a map is `nil`.
+A `nil` map has no keys, nor can they be added.
 
-The `make` function initializes an empty map of the given type.
+The `make` function returns a map of the given type,
+initialized and ready for use.
 
 .play moretypes/maps.go