Add note about len and [] operating on bytes

Fixes #148.

examples/string-functions/string-functions.go

@@ -14,10 +14,12 @@ var p = fmt.Println
 func main() {
 
     // Here's a sample of the functions available in
-    // `strings`. Note that these are all functions from the
-    // package, not methods on the string object itself.
-    // This means that we need pass the string in question
-    // as the first argument to the function.
+    // `strings`. Since these are functions from the
+    // package, not methods on the string object itself,
+    // we need pass the string in question as the first
+    // argument to the function. You can find more
+    // functions in the [`strings`](http://golang.org/pkg/strings/)
+    // package docs.
     p("Contains:  ", s.Contains("test", "es"))
     p("Count:     ", s.Count("test", "t"))
     p("HasPrefix: ", s.HasPrefix("test", "te"))
@@ -32,12 +34,16 @@ func main() {
     p("ToUpper:   ", s.ToUpper("test"))
     p()
 
-    // You can find more functions in the [`strings`](http://golang.org/pkg/strings/)
-    // package docs.
-
-    // Not part of `strings` but worth mentioning here are
-    // the mechanisms for getting the length of a string
-    // and getting a character by index.
+    // Not part of `strings`, but worth mentioning here, are
+    // the mechanisms for getting the length of a string in
+    // bytes and getting a byte by index.
     p("Len: ", len("hello"))
     p("Char:", "hello"[1])
 }
+
+// Note that `len` and indexing above work at the byte level.
+// Go uses UTF-8 encoded strings, so this is often useful
+// as-is. If you're working with potentially multi-byte
+// characters you'll want to use encoding-aware operations.
+// See [strings, bytes, runes and characters in Go](https://blog.golang.org/strings)
+// for more information.

examples/string-functions/string-functions.hash

@@ -1,2 +1,2 @@
-d7150ce50772abdaf827082093613134cb05e08f
-Gkc5rDaeaN
+17aa523bbd606fa0b624fae44b89812d46330755
+Lf5_Zbg6or