Update Readme.txt

Fixed documentation URI
Fix {JSON_OBJECT}.hash_code implementation

Don't call {HASH_TABLE}.item_for_iteration when {HASH_TABLE}.off
Use {HASH_TABLE}.out instead
Merge pull request #4 from oligot/fix_json_object_hash_code

Fix {JSON_OBJECT}.hash_code implementation
Merge pull request #3 from jvelilla/master

Fixed documentation URI