[yt-dev] Issue #793: Document the PlotWindow origin keyword (yt_analysis/yt)

New issue 793: Document the PlotWindow origin keyword https://bitbucket.org/yt_analysis/yt/issue/793/document-the-plotwindow-origi... Nathan Goldbaum: It looks like documentation for the origin keyword is missing. This should be added. Responsible: ngoldbaum