docs: consistent header sizing, small grammar changes (#366)
docs: consistent header sizing, small grammar changes (#366)


JustinBeckwith/google-auth-library-nodejs,JustinBeckwith/google-auth-library-nodejs,JustinBeckwith/google-auth-library-nodejs,googleapis/google-auth-library-nodejs,JustinBeckwith/google-auth-library-nodejs,googleapis/google-auth-library-nodejs