added missing documentation for sequence region post endpoint
added missing documentation for sequence region post endpoint

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