qmp-shell: add documentation

# (QEMU) device_add driver=e1000 id=net1

# {u'return': {}}

# (QEMU)

#

# key=value pairs also support Python or JSON object literal subset notations,

# without spaces. Dictionaries/objects {} are supported as are arrays [].

#

#    example-command arg-name1={'key':'value','obj'={'prop':"value"}}

#

# Both JSON and Python formatting should work, including both styles of

# string literal quotes. Both paradigms of literal values should work,

# including null/true/false for JSON and None/True/False for Python.

#

#

# Transactions have the following multi-line format:

#

#    transaction(

#    action-name1 [ arg-name1=arg1 ] ... [arg-nameN=argN ]

#    ...

#    action-nameN [ arg-name1=arg1 ] ... [arg-nameN=argN ]

#    )

#

# One line transactions are also supported:

#

#    transaction( action-name1 ... )

#

# For example:

#

#     (QEMU) transaction(

#     TRANS> block-dirty-bitmap-add node=drive0 name=bitmap1

#     TRANS> block-dirty-bitmap-clear node=drive0 name=bitmap0

#     TRANS> )

#     {"return": {}}

#     (QEMU)

#

# Use the -v and -p options to activate the verbose and pretty-print options,

# which will echo back the properly formatted JSON-compliant QMP that is being

# sent to QEMU, which is useful for debugging and documentation generation.

import qmp

import json