Update coroutines-guide.md (#3012)
Update coroutines-guide.md (#3012)

* Update coroutines-guide.md

"kotlinx.coroutines guide" Google search first result still leads here and it would be nice to guide people directly to kotlinlang

Co-authored-by: dkhalanskyjb <4981b4409fe971fac9e112eca32074e36381c092@users.noreply.github.com>
Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines