chore(markdown): Move non-api docs to reference

markdown/dev/reference/hooks/postsample/en.md

@@ -0,0 +1,30 @@
+---
+title: postSample
+---
+
+The `postSample` hook runs just after your pattern is sampled.
+
+## Signature
+
+```js
+null hook(Pattern pattern)
+```
+
+## Example
+
+```js
+pattern.on('postSample', pattern => {
+  // Mutate the pattern object here
+}
+```
+
+## Notes
+
+The `postSample` hook is rarely used, but it's there if you need it.
+
+It is triggered just before the end of either:
+
+- the [Pattern.sampleOption()](/reference/api/pattern/sampleoption) method
+- the [Pattern.sampleMeasurement()](/reference/api/pattern/samplemeasurement) method
+- the [Pattern.sampleModels()](/reference/api/pattern/samplemodels) method
+