Loop in a more rubyish way in Readme

Ruby devs generally iterate using the more functional methods rather than setting up an index and mutating it.
If this they are the target audience of this doc this would probably be clearer.

README.md

@@ -168,18 +168,12 @@ pointer = instance.exports.return_string
 memory = instance.memory.uint8_view pointer
 
 # Read the string pointed by the pointer.
-nth = 0
-string = ""
-
-while true
- char = memory[nth]
 
- if 0 == char
- break
- end
+string = ""
 
+memory.each do |char|
+ break if char == 0
  string += char.chr
- nth += 1
 end
 
 puts string # Hello, World!