docs(coroutine): add explanation for CoroutineContext and its elements

- Describe the parameters of launch/async methods for creating coroutines
- Explain the structure and elements of CoroutineContext
- Detail the purpose of each CoroutineContext element: - Job: coroutine handle/unique identifier
  - CoroutineDispatcher: specifies the thread for coroutine execution
  - CoroutineName: assigns a name to the coroutine for debugging
  - CoroutineExceptionHandler: specifies an exception handler for uncaught exceptions

Author: sinlov

dashboard/src/test/kotlin/com/sinlov/kotlin/playground/coroutine/CoroutinesMust.kt

@@ -0,0 +1,24 @@
+package com.sinlov.kotlin.playground.coroutine
+
+import io.kotest.core.spec.style.FunSpec
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.async
+
+class CoroutinesMust : FunSpec({
+    test("CoroutineContext") {
+        /**
+         * The method [launch]/[async] for creating coroutines has a total of 3 parameters,
+         * with the last one being the coroutine code block,
+         * and the other two parameters are used to control the coroutine.
+         */
+
+        /**
+         * [kotlin.coroutines.CoroutineContext] is a collection, the specific element type is [kotlin.coroutines.CoroutineContext.Element]
+         * Specific elements have four types.
+         * [kotlinx.coroutines.Job]：协程的句柄，或者说唯一标识，用以具体控制每个协程的（cancel和join等），具有树形关系
+         * [kotlinx.coroutines.CoroutineDispatcher]：用以指定协程的运行线程
+         * [kotlinx.coroutines.CoroutineName]：给协程取个名字，方便调试
+         * [kotlinx.coroutines.CoroutineExceptionHandler]：指定协程的异常处理器，用以处理未被捕获的异常
+         */
+    }
+})