Add contributors

[sohaamir]

@all-contributors please add @lei-zhang for code maintenance

[sohaamir]

@all-contributors please add @lei-zhang for code, maintenance

[allcontributors]

@sohaamir

I've put up a pull request to add @lei-zhang! 🎉

[sohaamir]

@all-contributors please add @sohaamir for code, maintenance

[allcontributors]

@sohaamir

I've put up a pull request to add @sohaamir! 🎉