fix: use jsdoc comments (#8)

Gives a nice little mouse-over in vscode when using this module

src/duplex.ts

@@ -1,6 +1,9 @@
 import { pair } from './index.js'
 import type { Duplex } from 'it-stream-types'
 
+/**
+ * Two duplex streams that are attached to each other
+ */
 export function duplexPair <T> (): [Duplex<T>, Duplex<T>] {
   const a = pair<T>()
   const b = pair<T>()

src/index.ts

@@ -1,7 +1,9 @@
 import defer from 'p-defer'
 import type { Source, Duplex } from 'it-stream-types'
 
-// a pair of streams where one drains from the other
+/**
+ * A pair of streams where one drains from the other
+ */
 export function pair <T> (): Duplex<T> {
   const deferred = defer<Source<T>>()
   let piped = false