Updated document

Updated readme,added about ipython

README.rst

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 ===========================================
  IPython: Productive Interactive Computing
 ===========================================
 
 Overview
 ========
 
 Welcome to IPython.  Our full documentation is available on `ipython.readthedocs.io
 <https://ipython.readthedocs.io/en/stable/>`_ and contains information on how to install, use, and
 contribute to the project.
+IPython (Interactive Python) is a command shell for interactive computing in multiple programming languages, originally developed for the Python programming language, that offers introspection, rich media, shell syntax, tab completion, and history.
 
 **IPython versions and Python Support**
 
 Starting with IPython 7.10, IPython follows `NEP 29 <https://numpy.org/neps/nep-0029-deprecation_policy.html>`_
 
 **IPython 7.17+** requires Python version 3.7 and above.
 
 **IPython 7.10+** requires Python version 3.6 and above.
 
 **IPython 7.0** requires Python version 3.5 and above.
 
 **IPython 6.x** requires Python version 3.3 and above.
 
 **IPython 5.x LTS** is the compatible release for Python 2.7.
 If you require Python 2 support, you **must** use IPython 5.x LTS. Please
 update your project configurations and requirements as necessary.
 
 
 The Notebook, Qt console and a number of other pieces are now parts of *Jupyter*.
 See the `Jupyter installation docs <https://jupyter.readthedocs.io/en/latest/install.html>`__
 if you want to use these.
 
 
 
 
 Development and Instant running
 ===============================
 
 You can find the latest version of the development documentation on `readthedocs
 <https://ipython.readthedocs.io/en/latest/>`_.
 
 You can run IPython from this directory without even installing it system-wide
 by typing at the terminal::
 
    $ python -m IPython
 
 Or see the `development installation docs
 <https://ipython.readthedocs.io/en/latest/install/install.html#installing-the-development-version>`_
 for the latest revision on read the docs.
 
 Documentation and installation instructions for older version of IPython can be
 found on the `IPython website <https://ipython.org/documentation.html>`_
 
 
 
 IPython requires Python version 3 or above
 ==========================================
 
 Starting with version 6.0, IPython does not support Python 2.7, 3.0, 3.1, or
 3.2.
 
 For a version compatible with Python 2.7, please install the 5.x LTS Long Term
 Support version.
 
 If you are encountering this error message you are likely trying to install or
 use IPython from source. You need to checkout the remote 5.x branch. If you are
 using git the following should work::
 
   $ git fetch origin
   $ git checkout 5.x
 
 If you encounter this error message with a regular install of IPython, then you
 likely need to update your package manager, for example if you are using `pip`
 check the version of pip with::
 
   $ pip --version
 
 You will need to update pip to the version 9.0.1 or greater. If you are not using
 pip, please inquiry with the maintainers of the package for your package
 manager.
 
 For more information see one of our blog posts:
 
     https://blog.jupyter.org/release-of-ipython-5-0-8ce60b8d2e8e
 
 As well as the following Pull-Request for discussion:
 
     https://github.com/ipython/ipython/pull/9900
 
 This error does also occur if you are invoking ``setup.py`` directly – which you
 should not – or are using ``easy_install`` If this is the case, use ``pip
 install .`` instead of ``setup.py install`` , and ``pip install -e .`` instead
 of ``setup.py develop`` If you are depending on IPython as a dependency you may
 also want to have a conditional dependency on IPython depending on the Python
 version::
 
     install_req = ['ipython']
     if sys.version_info[0] < 3 and 'bdist_wheel' not in sys.argv:
         install_req.remove('ipython')
         install_req.append('ipython<6')
 
     setup(
         ...
         install_requires=install_req
     )
 
 Alternatives to IPython
 =======================
 
 IPython may not be to your taste; if that's the case there might be similar
 project that you might want to use:
 
 - the classic Python REPL.
 - `bpython <https://bpython-interpreter.org/>`_
 - `mypython <https://www.asmeurer.com/mypython/>`_
 - `ptpython and ptipython <https://pypi.org/project/ptpython/>`
 - `xonsh <https://xon.sh/>`
 
 Ignoring commits with git blame.ignoreRevsFile
 ==============================================
 
 As of git 2.23, it is possible to make formatting changes without breaking
 ``git blame``. See the `git documentation
 <https://git-scm.com/docs/git-config#Documentation/git-config.txt-blameignoreRevsFile>`_
 for more details.
 
 To use this feature you must:
 
 - Install git >= 2.23
 - Configure your local git repo by running:
    - POSIX: ``tools\configure-git-blame-ignore-revs.sh``
    - Windows:  ``tools\configure-git-blame-ignore-revs.bat``