docs(public_reference): add LocalStack as a public reference (aws-powertools#4858)

Adding LocalStack as public ref

Author: leandrodamascena

README.md

@@ -65,6 +65,7 @@ The following companies, among others, use Powertools:
 * [globaldatanet](https://globaldatanet.com/)
 * [IMS](https://ims.tech/)
 * [Jit Security](https://www.jit.io/)
+* [LocalStack](https://www.localstack.cloud/)
 * [Propellor.ai](https://www.propellor.ai/)
 * [Recast](https://getrecast.com/)
 * [TopSport](https://www.topsport.com.au/)

docs/index.md

@@ -460,6 +460,9 @@ Knowing which companies are using this library is important to help prioritize t
 [**Jit Security**](https://www.jit.io/){target="_blank" rel="nofollow"}
 { .card }
 
+[**LocalStack**](https://www.localstack.cloud/){target="_blank" rel="nofollow"}
+{ .card }
+
 [**Propellor.ai**](https://www.propellor.ai/){target="_blank" rel="nofollow"}
 { .card }