Simple readme tweaks

README.rst

@@ -1,7 +1,10 @@
-.. image:: docs/logos/jdaviz.svg
-    :width: 400
-    :alt: Jdaviz logo
-    :align: center
+.. raw:: html
+
+   <div align="center">
+   <img src="docs/logos/jdaviz.svg" width="400px" alt="Jdaviz logo">
+   </img>
+   <br /><br />
+   </div>
 
 .. image:: https://zenodo.org/badge/DOI/10.5281/zenodo.5513927.svg
     :target: https://doi.org/10.5281/zenodo.5513927
@@ -96,7 +99,7 @@ The power of ``jdaviz`` is that it can integrated into your Jupyter notebook wor
     from jdaviz import Specviz
 
     specviz = Specviz()
-    specviz.app
+    specviz.show()
 
 To learn more about the various ``jdaviz`` application configurations and loading data, see the
 `specviz <https://jdaviz.readthedocs.io/en/latest/specviz/import_data.html>`_, `cubeviz <https://jdaviz.readthedocs.io/en/latest/cubeviz/import_data.html>`_, `mosviz <https://jdaviz.readthedocs.io/en/latest/mosviz/import_data.html>`_, or `imviz <https://jdaviz.readthedocs.io/en/latest/imviz/import_data.html>`_ tools.