README.md

NOTE: $:/core has been updated with the following VR-fixes nearby SandBoxToken:

this.tree[0].attributes.allowvr = {type: \"string\", value:\"yes\"};
this.tree[0].attributes.allowfullscreen = {type: \"string\", value:\"yes\"}
this.tree[0].attributes.frameborder = {type: \"string\", value:\"0\"}