chore(github): add type to issue templates (#8775)

# Which Problems Are Solved

Github introduced the new issue types, which we want to add to our
issues. Starting point is to change the templates, so we can add the
right types.

.github/ISSUE_TEMPLATE/docs.yaml

@@ -1,6 +1,7 @@
 name: 📄 Documentation
 description: Create an issue for missing or wrong documentation.
 labels: ["docs"]
+type: task
 body:
   - type: markdown
     attributes:

.github/ISSUE_TEMPLATE/enhancement.yaml

@@ -1,6 +1,7 @@
 name: 💡 Proposal / Feature request
 description: "Create an issue for a feature request/proposal."
 labels: ["enhancement"]
+type: enhancement
 body:
   - type: markdown
     attributes:

.github/ISSUE_TEMPLATE/improvement.yaml

@@ -1,54 +0,0 @@
-name: 🛠️ Improvement
-description: "Create an new issue for an improvment in ZITADEL"
-labels: ["improvement"]
-body:
-  - type: markdown
-    attributes:
-      value: |
-        Thanks for taking the time to fill out this improvement request
-  - type: checkboxes
-    id: preflight
-    attributes:
-      label: Preflight Checklist
-      options:
-      - label:
-          I could not find a solution in the existing issues, docs, nor discussions
-        required: true
-      - label:
-          I have joined the [ZITADEL chat](https://zitadel.com/chat)
-  - type: textarea
-    id: problem
-    attributes:
-      label: Describe your problem
-      description: Please describe your problem this improvement is supposed to solve.
-      placeholder: Describe the problem you have
-    validations:
-      required: true
-  - type: textarea
-    id: solution
-    attributes:
-      label: Describe your ideal solution
-      description: Which solution do you propose?
-      placeholder: As a [type of user], I want [some goal] so that [some reason].
-    validations:
-      required: true
-  - type: input
-    id: version
-    attributes:
-      label: Version
-      description: Which version of the ZITADEL are you using.
-  - type: dropdown
-    id: environment
-    attributes:
-      label: Environment
-      description: How do you use ZITADEL?
-      options:
-      - ZITADEL Cloud
-      - Self-hosted
-    validations:
-      required: true
-  - type: textarea
-    id: additional
-    attributes:
-      label: Additional Context
-      description: Please add any other infos that could be useful.