docs: Fix a few typos

[timgates42]

There are small typos in:

• QUICKSTART.md
• src/parser.c

Fixes:

• Should read idiomatic rather than idomatic.
• Should read generated rather than genrated.
• Should read function rather than funciton.

Semi-automated pull request generated by https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

[LingDong-]

Thanks!