Fix typo in gitignore (#19638)
Fix typo in gitignore (#19638)

Build directory is `dist` and not `build`. The typo also makes gitignore not work correctly.
flybayer/next.js,azukaru/next.js,flybayer/next.js,azukaru/next.js,flybayer/next.js,azukaru/next.js,zeit/next.js,JeromeFitz/next.js,zeit/next.js,JeromeFitz/next.js,zeit/next.js,flybayer/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js