Remove psaces from some filenames.

diff --git a/docs/notebooks/Joy in Jupyter.ipynb b/docs/notebooks/Joy-in-Jupyter.ipynb
similarity index 100%
rename from docs/notebooks/Joy in Jupyter.ipynb
rename to docs/notebooks/Joy-in-Jupyter.ipynb

diff --git a/docs/notebooks/Multiples of 3 and 5.ipynb b/docs/notebooks/Multiples-of-3-and-5.ipynb
similarity index 100%
rename from docs/notebooks/Multiples of 3 and 5.ipynb
rename to docs/notebooks/Multiples-of-3-and-5.ipynb