chore(docs): remove GitHub Discussions references and update support channels (#5292)

fix https://github.com/external-secrets/external-secrets/issues/5283

Signed-off-by: Jakob Möller <jakob.moeller@sap.com>

README.md

@@ -17,7 +17,7 @@ To ensure the long-term health of the project, we are temporarily pausing all of
 
 ✅ Contributions will be available on the main branch.
 
-❌ We will not provide support via GitHub Discussions, Slack, or issue comments.
+❌ We will not provide support via Slack, or issue comments.
 
 ❌ We will not publish any new releases (major, minor, or patch), including 0.19.x and 1.0.x.
 

docs/contributing/process.md

@@ -144,8 +144,7 @@ Providing support to end users is an important and difficult task.
 We have three different channels through which support questions arise:
 
 1. Kubernetes Slack [#external-secrets](https://kubernetes.slack.com/archives/C017BF84G2Y)
-2. [GitHub Discussions](https://github.com/external-secrets/external-secrets/discussions)
-3. GitHub Issues
+2. [GitHub Issues](https://github.com/external-secrets/external-secrets/issues/new/choose)
 
 We use labels to identify GitHub Issues. Specifically for managing support cases we use the following labels to identify the state a support case is in: