fixed typo in page-without-valid-component.md (#15022)
fixed typo in page-without-valid-component.md (#15022)


JeromeFitz/next.js,flybayer/next.js,flybayer/next.js,flybayer/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,JeromeFitz/next.js,zeit/next.js,azukaru/next.js,azukaru/next.js,flybayer/next.js,zeit/next.js,zeit/next.js,azukaru/next.js