Remove .env.shared file and reference in docs

Author: jarbesfeld

.env.shared

@@ -70,8 +70,6 @@ Cool-Seq-Tool's dependencies can be installed using a Docker container. We only
    This section assumes you have a local
    `SeqRepo <https://github.com/biocommons/biocommons.seqrepo>`_
    installed at ``/usr/local/share/seqrepo/2024-12-20``.
-   If you have it installed elsewhere, please add a
-   ``SEQREPO_ROOT_DIR`` environment variable in ``.env.shared``.
    See the `SeqRepo setup section <#set-up-seqrepo>`_ for additional information.
 
    You must download `uta_20241220.pgd.gz` from