Tweaks for String#bytesize

doc/string/bytesize.rdoc

@@ -1,11 +1,15 @@
-Returns the count of bytes (not characters) in +self+:
+Returns the count of bytes in +self+.
 
-  'foo'.bytesize        # => 3
-  'тест'.bytesize       # => 8
-  'こんにちは'.bytesize   # => 15
+Note that the byte count may be different from the character count (returned by #size):
 
-Contrast with String#length:
+  s = 'foo'
+  s.bytesize # => 3
+  s.size     # => 3
+  s = 'тест'
+  s.bytesize # => 8
+  s.size     # => 4
+  s = 'こんにちは'
+  s.bytesize # => 15
+  s.size     # => 5
 
-  'foo'.length       # => 3
-  'тест'.length      # => 4
-  'こんにちは'.length  # => 5
+Related: see {Querying}[rdoc-ref:String@Querying].