Added migration HTML to Markdown migration script documentation
Added migration HTML to Markdown migration script documentation

proyectos-analizo-info/pybossa-analizo-info,PyBossa/pybossa,stefanhahmann/pybossa,OpenNewsLabs/pybossa,harihpr/tweetclickers,CulturePlex/pybossa,jean/pybossa,OpenNewsLabs/pybossa,PyBossa/pybossa,jean/pybossa,harihpr/tweetclickers,Scifabric/pybossa,CulturePlex/pybossa,geotagx/pybossa,geotagx/pybossa,inteligencia-coletiva-lsd/pybossa,stefanhahmann/pybossa,inteligencia-coletiva-lsd/pybossa,CulturePlex/pybossa,Scifabric/pybossa,proyectos-analizo-info/pybossa-analizo-info,proyectos-analizo-info/pybossa-analizo-info