remove redundant `typeof` example from README
remove redundant `typeof` example from README

kemitchell/spdx-expression-parse.js,kasicka/spdx.js,jslicense/spdx-expression-parse.js,kemitchell/spdx.js,kemitchell/spdx-expression-validate.js,pombredanne/spdx-expression-validate.js,pombredanne/spdx.js,pombredanne/spdx-expression-parse.js