docs: Update README with codegen instructions

README.md

@@ -13,10 +13,27 @@ An IPFS Pinning Service HTTP Client
 
 [Adin Schmahmann](https://github.com/aschmahmann)
 
+## Updating Pinning Service Spec
+
+Download the openapi-generator from https://github.com/OpenAPITools/openapi-generator and generate the code using:
+
+Current code generated with: openapi-generator 5.0.0-beta
+
+```
+openapi-generator generate -g go-experimental -i https://raw.githubusercontent.com/ipfs/pinning-services-api-spec/master/ipfs-pinning-service.yaml -o openapi
+rm openapi/go.mod openapi/go.sum
+```
+
+Notes:
+Due to https://github.com/OpenAPITools/openapi-generator/issues/7473 the code generator the http error codes processing
+may need some manual editing.
+
+`go-experimental` is becoming mainstream and so in later versions will be replaced with `go`
+
 ## Contributing
 
 Contributions are welcome! This repository is part of the IPFS project and therefore governed by our [contributing guidelines](https://github.com/ipfs/community/blob/master/CONTRIBUTING.md).
 
 ## License
 
-[SPDX-License-Identifier: Apache-2.0 OR MIT](LICENSE.md)
+[SPDX-License-Identifier: Apache-2.0 OR MIT](LICENSE.md)
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