Add COTTAS store backend (#3139)

Author: arenas-guerrero-julian

docs/plugin_stores.rst

@@ -28,15 +28,16 @@ External
 The following Stores are defined externally to rdflib's core package, so look to their documentation elsewhere for 
 specific details of use.
 
-================= ==================================================== =============================================================================================
-Name              Repository                                           Notes
-================= ==================================================== =============================================================================================
-SQLAlchemy        `<https://github.com/RDFLib/rdflib-sqlalchemy>`_     An SQLAlchemy-backed, formula-aware RDFLib Store. Tested dialects are: SQLite, MySQL & PostgreSQL
-leveldb           `<https://github.com/RDFLib/rdflib-leveldb>`_        An adaptation of RDFLib BerkeleyDB Store’s key-value approach, using LevelDB as a back-end
-Kyoto Cabinet     `<https://github.com/RDFLib/rdflib-kyotocabinet>`_   An adaptation of RDFLib BerkeleyDB Store’s key-value approach, using Kyoto Cabinet as a back-end
-HDT               `<https://github.com/RDFLib/rdflib-hdt>`_            A Store back-end for rdflib to allow for reading and querying `HDT <https://www.rdfhdt.org/>`_ documents
-Oxigraph          `<https://github.com/oxigraph/oxrdflib>`_            Works with the `Pyoxigraph <https://oxigraph.org/pyoxigraph>`_ Python graph database library
-================= ==================================================== =============================================================================================
+================= ======================================================== =============================================================================================
+Name              Repository                                               Notes
+================= ======================================================== =============================================================================================
+SQLAlchemy        `<https://github.com/RDFLib/rdflib-sqlalchemy>`_         An SQLAlchemy-backed, formula-aware RDFLib Store. Tested dialects are: SQLite, MySQL & PostgreSQL
+leveldb           `<https://github.com/RDFLib/rdflib-leveldb>`_            An adaptation of RDFLib BerkeleyDB Store’s key-value approach, using LevelDB as a back-end
+Kyoto Cabinet     `<https://github.com/RDFLib/rdflib-kyotocabinet>`_       An adaptation of RDFLib BerkeleyDB Store’s key-value approach, using Kyoto Cabinet as a back-end
+HDT               `<https://github.com/RDFLib/rdflib-hdt>`_                A Store back-end for rdflib to allow for reading and querying `HDT <https://www.rdfhdt.org/>`_ documents
+Oxigraph          `<https://github.com/oxigraph/oxrdflib>`_                Works with the `Pyoxigraph <https://oxigraph.org/pyoxigraph>`_ Python graph database library
+pycottas          `<https://github.com/arenas-guerrero-julian/pycottas>`_  A Store backend for querying compressed `COTTAS <https://pycottas.readthedocs.io/#cottas-files>`_ files
+================= ======================================================== =============================================================================================
 
 *If you have, or know of a Store implementation and would like it listed here, please submit a Pull Request!*