Document default word wrap of 80 in readme (#162)

examples/custom_renderer/main.go

@@ -9,11 +9,7 @@ import (
 func main() {
 	in := `# Custom Renderer
 
-Word-wrapping will occur when lines exceed the limit of 40 characters. Just so
-you know: Glamour's default word-wrapping limit is set to 100 characters per
-line.
-
-Bye!
+Word-wrapping will occur when lines exceed the limit of 40 characters.
 `
 
 	r, _ := glamour.NewTermRenderer(