Add extra markdow extensions to pelicanconf

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
add Prepare development environment to guide

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Add Create metadata file to guide

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>