*Tiny* changes to anchors in README
*Tiny* changes to anchors in README

Anchors are case-sensitive by specification, so "#Clients" does not work.
Some anchors were not relative, and were corrected.
connor4312/toxiproxy,di-stars/toxiproxy,akshatknsl/toxiproxy,Shopify/toxiproxy,Shopify/toxiproxy,ihsw/toxiproxy