content: use Pizza/pizza as an example of exported names

In other languages, all-caps usually signifies an exported constant.
Remove that example since it conflicts with Go's naming guide.

Fixes golang/go#15047.

Change-Id: I7af4a125ad1ba4bd9dd10a0e63eff8e4125cff00
Reviewed-on: https://go-review.googlesource.com/21387
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/content/basics.article b/content/basics.article
index 230ddeb..fd17b60 100644
--- a/content/basics.article
+++ b/content/basics.article
@@ -38,12 +38,14 @@
 * Exported names
 
 In Go, a name is exported if it begins with a capital letter.
+For example, `Pizza` is an exported name, as is `Pi`, which is exported from
+the `math` package.
+
+`pizza` and `pi` do not start with a capital letter, so they are not exported.
 
 When importing a package, you can refer only to its exported names.
 Any "unexported" names are not accessible from outside the package.
 
-`Pi` is an exported name, as is `PI`. The name `pi` is not exported.
-
 Run the code. Notice the error message.
 
 To fix the error, rename `math.pi` to `math.Pi` and try it again.