Updated readme on plugin folder

Signed-off-by: Thomas Seng Hin Mak <makzan@gmail.com>
Added .jstalk note in readme

Signed-off-by: Thomas Seng Hin Mak <makzan@gmail.com>
Added 2 plugins: fill_width and fill_height

Signed-off-by: Thomas Seng Hin Mak <makzan@gmail.com>