Add timeout parameter

[chinapedia]

From https://pandoc.org/MANUAL.html#a-note-on-security

Pandoc’s parsers can exhibit pathological performance on some corner cases. It is wise to put any pandoc operations under a timeout, to avoid DOS attacks that exploit these issues. If you are using the pandoc executable, you can add the command line options +RTS -M512M -RTS (for example) to limit the heap size to 512MB.