Add note about jbig error
Add note about jbig error

From PR #900, this should be properly resolved, include workaround until it is.
janisozaur/opentoonz,m-grimaud/opentoonz,janisozaur/opentoonz,m-grimaud/opentoonz,damies13/opentoonz,m-grimaud/opentoonz,janisozaur/opentoonz,lordadamson/opentoonz,damies13/opentoonz,lordadamson/opentoonz,damies13/opentoonz,m-grimaud/opentoonz,damies13/opentoonz,m-grimaud/opentoonz,lordadamson/opentoonz,lordadamson/opentoonz,janisozaur/opentoonz,janisozaur/opentoonz,damies13/opentoonz,lordadamson/opentoonz