feat: examples to demonstrate the usage of changeset

Signed-off-by: Yulong Ruan <ruanyl@amazon.com>

.changeset/heavy-tigers-sell.md

@@ -0,0 +1,16 @@
+---
+'opensearch-dashboards': minor
+---
+
+## This is an example of using changeset
+
+In this example, there are some changes to `opensearch-dashboards`. But this is
+just for demo, there is no changes to the actual files.
+
+This is a example to demonstrate the idea of using changeset to manage
+changelog without tears.
+
+The changeset file is a regular markdown file, we can use markdown syntax:
+```
+yarn changeset add
+```

.changeset/lucky-pears-listen.md

@@ -0,0 +1,10 @@
+---
+'@osd/opensearch': patch
+---
+
+## Another example to demonstrate changes to workspace packages
+
+In this example, there are some changes to package `@osd/opensearch`. But this is
+just for demo, there is no changes to the actual files.
+
+Ideally, we want to document each and every changes clearly of each package.