Issue #77 - Refactor docstrings in rST format - part 1
    
    Decsription: With the first part, refactor docstrings in modules:
    _mapped_object.py, aci.py, agreement.py, backend.py,
    changelog.py, mappingTree.py, replica.py, repltools.py
    
    Format it properly and put to index.rst
    
    Add a script for links to the code in the docs.
    
    https://pagure.io/lib389/issue/77
    
    Reviewed by: wibrown (Thanks!)