installing_duckpan.md: Copied over the README from p5-app-duckpan
installing_duckpan.md: Typos
installing_duckpan.md: Wording changes by @mwmiller
Merge pull request #82 from duckduckgo/jag/p5-to

installing_duckpan.md: Copied over the README from p5-app-duckpan