fix spelling errors

I created a new bugfix branch and copied over a clone of a recent version of your repository (commit "Large update for the interactive map" e58b45d85607cd83a7ec5fc41d33ded7da79ed00).  Then, I fixed a few spelling errors.  If you check the diff, you'll see that the changes are small.  However, Git is pulling in the history of my commits starting from when I forked your project - I guess you might not want this.  If you want to keep the commit history clean, you could make copies of the files I changed and commit the changes yourself rather than pull in 24 commits from my pull request.