CONTRIBUTING: Spelling fix, propoals -> proposals
CONTRIBUTING: Spelling fix, propoals -> proposals

Signed-off-by: Edward Haas <416ab6a6c3e37a8cab0d365516e79cce8f9be5ad@redhat.com>

davidvossel/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt