fix typo in rst markup

[anntzer]

in http://matplotlib.org/tutorials/advanced/transforms_tutorial.html#transformations-tutorial:

• remove extra backquotes after transData
• the last row of the table was incorrectly split; looks like I need a grid table to get around that (http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#simple-tables: "Also, this mechanism limits cells in the first column to only one line of text. Use grid tables if this limitation is unacceptable.")

PR Summary

PR Checklist

• Has Pytest style unit tests
• Code is PEP 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way