Add a README to analysis_tools

README.rst

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+==============
 analysis_tools
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+==============
 
-``analysis_tools`` is a package in the `LSST Science Pipelines <https://pipelines.lsst.io>`_.
+The Analysis Tools package is designed to assist in the creation of quality assurance (QA) plots and metrics from the outputs of an `LSST data reduction pipeline <https://pipelines.lsst.io/modules/lsst.pipe.base/creating-a-pipeline.html>`_.
+The intention is that users have the flexibility to construct complex data analysis tasks from a set of simple building blocks.
+These analysis tools therefore allow users to generate a series of consistent, repeatable and high-quality plots and metrics, regardless of which dataset they are run on.
 
-.. Add a brief (few sentence) description of what this package provides.
+For more information on using the Analysis Tools package, please see the documentation on `pipelines.lsst.io <https://pipelines.lsst.io/modules/lsst.analysis_tools/index.html>`_.
+As this package is still under active development, it may be useful to see the latest `daily build of the documentation <https://pipelines.lsst.io/v/daily/index.html>`_ as well.