docs: add testing and mocks section to readme

Signed-off-by: Boris Glimcher <36732377+glimchb@users.noreply.github.com>

README.md

@@ -56,3 +56,21 @@ docker-compose exec opi-evpn-bridge grpcurl -plaintext -d '{"name" : "//network.
 ![OPI EVPN Bridge Diagram for L3VXLAN Symmetric IRB](./docs/OPI-EVPN-L3-Symmetric-IRB.png)
 ![OPI EVPN Bridge Diagram for L2VXLAN in_Symmetric IRB](./docs/OPI-EVPN-L2-VXLAN-In-Symmetric-IRB-setup.png)
 ![OPI EVPN Bridge Diagram for Leaf1_Detailed_View](./docs/OPI-EVPN-Leaf1-Detailed-View.png)
+
+## Tests
+
+Test your APIs even if unmerged using your private fork like this:
+
+```bash
+chmod a+w go.*
+docker run --rm -it -v `pwd`:/app -w /app golang:alpine go mod edit -replace github.com/opiproject/opi-api@main=github.com/YOURUSERNAME/opi-api@main
+docker run --rm -it -v `pwd`:/app -w /app golang:alpine go get -u github.com/YOURUSERNAME/opi-api/storage/v1alpha1/gen/go@a98ca449468a
+docker run --rm -it -v `pwd`:/app -w /app golang:alpine go mod tidy
+```
+
+Generate mocks like this:
+
+```bash
+go install github.com/vektra/mockery/v2@latest
+make mock-generate
+```