Change in README file type and addition of installation README

INSTALL.rst

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+Installation Instructions
+==================
+The GalSim-Euclid-Like repository contains two python libraries and currently supports Python versions 3.10 and above.
+
+System requirements: Given the heavy dependance on GalSim, GalSim-Euclid-Like currently only supports Linux and Mac OSX. For 
+further details on system requirements for GalSim see `GalSim Installation <https://github.com/GalSim-developers/GalSim/blob/main/INSTALL.rst>`_.
+
+Dependencies
+----------------
+
+GalSim-Euclid-Like requires ``python>=3.10`` and the following dependencies::
+
+    numpy>=1.17,
+    galsim>=2.6,
+    astropy>=2.0
+
+Installation
+----------------
+The source code for GalSim-Euclid-Like has not been published to pypi. To install from source code::
+
+    git clone [email protected]:GalSim-developers/GalSim-Euclid-Like.git
+
+and install by running::
+
+    conda create -n euclidlike python=3.10
+    cd GalSim-Euclid-Like
+    conda activate euclidlike
+    pip install .
+
+To make sure the installation is successful, do the following::
+
+    $ python
+    >>> import euclidlike
+    >>> euclidlike.getBandpasses()

README.rst

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+GalSim-Euclid-Like
+==================
+
+Helper functions to generate simulations of Euclid-like images using GalSim.
+
+This repository contains information about the Euclid space telescope and survey that is needed to
+produce simulations using `GalSim <https://github.com/GalSim-developers/GalSim>`_.  Some of the
+information provided is approximate, aimed towards fast simulations rather than full accuracy in
+representation of Euclid images.  Places where the information is only approximate are flagged and
+described in the docstring, and we particularly highlight that the PSF is only approximate;
+for details, see the docstring of the ``getPSF()`` method.  This library should enable generation of
+Euclid-like images of sufficient fidelity for preliminary exploration of object detection,
+photometry, deblending, and joint analysis with ground-based observatories.  For
+applications requiring high precision such as weak lensing, the higher fidelity simulations
+available within the Euclid Consortium should be used.
+
+This repository includes two distinct packages:
+
+* ``euclidlike``: has basic observatory, instrumentation, and survey information for Euclid.
+  This package can be used on its own along with GalSim to produce Euclid-like simulations.
+
+* ``euclidlike_imsim``: has configuration scripts to produce large-scale Euclid-like simulation runs
+  based on the information in ``euclidlike``. It is based heavily on `roman_imsim <https://github.com/matroxel/roman_imsim>`_.
+
+
+References
+==================
+
+For more information about `GalSim <https://github.com/GalSim-developers/GalSim>`_, please see its README and documentation.
+
+For more information about Euclid, please see the `Euclid Consortium website <https://www.euclid-ec.org/>`_ and papers linked from there.
+
+Attribution for software and data used by particular routines in this library is given in the docstring for the relevant routine.
+
+Installation
+==================
+
+Please view the `installation instructions <INSTALL.rst>`_ for details on how to install GalSim-Euclid-Like.
+
+Downloading relevant data
+==================                                                                              
+The Euclid-like PSF is constructed from precomputed oversampled images on a grid in focal plane position and wavelength. To use the full FOV PSF within GalSim-Euclid-Like, the images must be downloaded by running::
+
+    $ euclidlike_download_psf
+
+in the terminal after installation of GalSim-Euclid-Like. To install in an alternative directory to the default, use the ``--dir`` argument. Refer to the ``getPSF`` documentation for further details about the PSF. 
+
+Getting started
+==================                                                                             
+
+Please see the examples/ directory for demos illustrating the use of this code.
+
+Communicating with the developers
+==================
+Feel free to `open a GitHub issue <https://github.com/GalSim-developers/GalSim-Euclid-Like/issues>`_ to reach the developers with questions, comments, and bug reports.  New contributors are also welcome and can indicate their interest in developing this code base through the Issues.
+
+Attribution
+==================                                   
+
+This software is open source and may be used according to the terms of its `license <LICENSE>`_.
+
+When using this software, please provide the URL to the repository in the resulting paper or note.  Once there is a Zenodo DOI or journal article, this README will be updated and we will ask those using the code in their research to cite the relevant journal article.
+