[CHORE] add XAU and XAG to value trends
[CHORE] add XAU and XAG to value trends

shekenahglory/ripplecharts-frontend,bekkibolthouse/stellar-charts-frontend,vahaknp/ripplecharts-frontend,bankonme/ripplecharts-frontend,Payshares/payshares-chart-frontend,bankonme/ripplecharts-frontend,ripple/ripplecharts-frontend,shekenahglory/ripplecharts-frontend,Payshares/payshares-chart-frontend,xdv/ripplecharts-frontend,ripple/ripplecharts-frontend,Payshare/stellar-charts-frontend,xdv/ripplecharts-frontend,Payshare/stellar-charts-frontend,bsteinlo/ripplecharts-frontend