added documentation and example queries for translation endpoint
added documentation and example queries for translation endpoint

ens-lgil/ensembl-rest,helensch/ensembl-rest,helensch/ensembl-rest,helensch/ensembl-rest,willmclaren/ensembl-rest,ens-lgil/ensembl-rest,willmclaren/ensembl-rest,ens-lgil/ensembl-rest,willmclaren/ensembl-rest,willmclaren/ensembl-rest,helensch/ensembl-rest,ens-lgil/ensembl-rest,helensch/ensembl-rest,willmclaren/ensembl-rest,ens-lgil/ensembl-rest