Move readme parts to their corresponding packages

threadpool/README.md

@@ -0,0 +1,22 @@
+## Thread pool
+
+Package `thread_pool` implements a pool of threads, duh.
+
+```go
+import "github.com/localhots/gobelt/threadpool"
+```
+
+```go
+ctx := context.Background()
+ctx, cancel = context.WithTimeout(ctx, 30*time.Second)
+defer cancel()
+
+pool := threadpool.New(10)
+defer pool.Close()
+for i := 0; i < 1000000; i++ {
+    i := i
+    pool.Enqueue(ctx, func() {
+        fmt.Printf("The number is %d\n", i)
+    })
+}
+```