README: Explain how to view the conference schedule locally on Linux

Added explanations using both Python and PHP which come with a built-in web server.
Not sure whether to add an explanation for Windows, don't know if there's a similar easy solution...
README: Explain how to view the conference schedule locally on Linux

Fixed typos and code blocks.
Merge pull request #13 from kiltec/master

Added description about how to get to the schedule locally