docs(timer): add timer reference

docs/.vitepress/config.mts

@@ -49,6 +49,7 @@ export default defineConfig({
             { text: "option", link: "/reference/option" },
             { text: "result", link: "/reference/result" },
             { text: "threadpool", link: "/reference/threadpool" },
+            { text: "timer", link: "/reference/timer" },
           ],
         },
       ],

docs/reference/index.md

@@ -7,3 +7,4 @@
 | [option](/reference/option)         | Values that may or may not exist.                          |
 | [result](/reference/result)         | Represent fallible operations.                             |
 | [threadpool](/reference/threadpool) | Spawn threads with reuse.                                  |
+| [timer](/reference/timer)           | Schedule code to run at a future time or at an interval.   |

docs/reference/timer.md

@@ -0,0 +1,58 @@
+---
+outline: [2, 3]
+---
+
+<script setup>
+import { data } from "./package-versions.data.ts";
+</script>
+
+# timer
+
+`timer` allows you to schedule code to run at a future time or at an interval.
+
+## Installation
+
+Learn more about [installation](/docs/getting-started#installation).
+
+::: code-group
+
+```toml-vue [Wally]
+timer = "lukadev-0/timer@{{ data.timer }}"
+```
+
+```lua [Bundle]
+local util = require(...)
+util.timer.delay(...)
+```
+
+:::
+
+## Functions
+
+### timer.delay
+
+```lua
+function timer.delay(duration: number): Future<number>
+```
+
+Returns a future that resolves after the given duration in seconds, returning
+the amount of time it took to resolve.
+
+This is equivalent to the following code:
+
+```lua
+local fut = Future.spawn(task.wait, duration)
+```
+
+### timer.interval
+
+```lua
+function timer.interval(duration: number, callback: function): () -> ()
+```
+
+Calls the given callback every `duration` seconds.
+
+This will correct for drift, it repeatedly calls `task.wait` and calculates
+the amount of time until the next call.
+
+Returns a function that will stop the interval when called.