docs: spelling error

[rogerogers]

What type of PR is this?

docs: spelling error

What this PR does / why we need it (en: English/zh: Chinese):

en: netpoll getting started doc spell error
zh: netpoll快速开始文档拼写错误

Which issue(s) this PR fixes:

[CLAassistant]

All committers have signed the CLA.

[li-jin-gou]

ci: Changes to our CI configuration files and scripts (example scopes: Travis, Circle, BrowserStack, SauceLabs)
docs: Documentation only changes
feat: A new feature
optimize: A new optimization
fix: A bug fix
perf: A code change that improves performance
refactor: A code change that neither fixes a bug nor adds a feature
style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
test: Adding missing tests or correcting existing tests
chore: Changes to the build process or auxiliary tools and libraries such as documentation generation

这个是 docs @rogerogers

[rogerogers]

ci: Changes to our CI configuration files and scripts (example scopes: Travis, Circle, BrowserStack, SauceLabs)
docs: Documentation only changes
feat: A new feature
optimize: A new optimization
fix: A bug fix
perf: A code change that improves performance
refactor: A code change that neither fixes a bug nor adds a feature
style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
test: Adding missing tests or correcting existing tests
chore: Changes to the build process or auxiliary tools and libraries such as documentation generation

这个是 docs @rogerogers

OK👌