chore: document crd upgrades (#361)

Signed-off-by: Todd Baert <[email protected]>

Author: toddbaert

docs/installation.md

@@ -19,8 +19,41 @@ Install the latest helm release:
 ```sh
 helm repo add openfeature https://open-feature.github.io/open-feature-operator/
 helm repo update
-helm upgrade -i openfeature openfeature/open-feature-operator
+helm upgrade --install openfeature openfeature/open-feature-operator
 ```
+### Upgrading
+
+```sh
+helm upgrade --install openfeature openfeature/open-feature-operator
+```
+
+#### Upgrading CRDs
+
+CRDs are not upgraded automatically with helm (https://helm.sh/docs/chart_best_practices/custom_resource_definitions/).
+OpenFeature Operator's CRDs are templated, and can be updated apart from the operator itself by using helm's template functionality and piping the output to `kubectl`:
+
+```sh
+helm template openfeature/open-feature-operator -s templates/{CRD} | kubectl apply -f -
+```
+
+For the `featureflagconfigurations.core.openfeature.dev` CRD:
+
+```sh
+helm template openfeature/open-feature-operator -s templates/apiextensions.k8s.io_v1_customresourcedefinition_featureflagconfigurations.core.openfeature.dev.yaml | kubectl apply -f -
+```
+
+For the `flagsourceconfigurations.core.openfeature.dev` CRD:
+
+```sh
+helm template openfeature/open-feature-operator -s templates/apiextensions.k8s.io_v1_customresourcedefinition_flagsourceconfigurations.core.openfeature.dev.yaml | kubectl apply -f -
+```
+
+Keep in mind, you can set values as usual during this process:
+
+```sh
+helm template openfeature/open-feature-operator -s templates/{CRD} --set defaultNamespace=myns | kubectl apply -f -
+```
+
 ### Uninstall
 ```sh
 helm uninstall ofo