update to working link example in docs and removed typo in contributing docs

Author: RRosio

CONTRIBUTING.rst

@@ -71,7 +71,7 @@ If you are working in development mode, you will see that your version of Jupyte
 Troubleshooting the Installation
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-If you do not see that your Jupyter Notebook is not running on dev mode, it's possible that you are
+If you do not see that your Jupyter Notebook is running on dev mode, it's possible that you are
 running other instances of Jupyter Notebook. You can try the following steps:
 
 1. Uninstall all instances of the notebook package. These include any installations you made using

docs/source/examples/Notebook/Distributing Jupyter Extensions as Python Packages.ipynb

@@ -134,7 +134,7 @@
     "\n",
     "> Of course, in addition to the files listed, there are number of other files one needs to build a proper package. Here are some good resources:\n",
     "- [The Hitchhiker's Guide to Packaging](https://the-hitchhikers-guide-to-packaging.readthedocs.io/en/latest/quickstart.html)\n",
-    "- [Repository Structure and Python](https://kenreitz.org/essays/2013/01/27/repository-structure-and-python) by Kenneth Reitz\n",
+    "- [Structure of the Repository](https://docs.python-guide.org/writing/structure/) by Kenneth Reitz and Real Python\n",
     "\n",
     "> How you distribute them, too, is important:\n",
     "- [Packaging and Distributing Projects](https://python-packaging-user-guide.readthedocs.io/tutorials/distributing-packages/)\n",