added completer issue template (#2431)

.github/ISSUE_TEMPLATE/completer.yaml

@@ -0,0 +1,64 @@
+name: Completer
+description: Request a new Completer
+title: "completer: <title>"
+labels: [enhancement, completer, polar]
+body:
+- type: input
+  attributes:
+    label: Name
+    description: Name of the command (as typed on the command line).
+  validations:
+    required: true
+- type: textarea
+  attributes:
+    label: Description
+    description: Short description of the command (just a sentence about what it is or does).
+  validations:
+    required: true
+- type: input
+  attributes:
+    label: Homepage
+    description: Homepage of the command (or repository if there is none).
+  validations:
+    required: true
+- type: input
+  attributes:
+    label: Documentation
+    description: Documentation of the command (if available).
+  validations:
+    required: false
+- type: input
+  attributes:
+    label: Repository
+    description: Repository of the command (if available).
+  validations:
+    required: false
+- type: checkboxes
+  attributes:
+    label: OS
+    description: Operating System the command supports.
+    options:
+    - label: Linux
+    - label: OSX
+    - label: Termux
+    - label: Windows
+- type: dropdown
+  attributes:
+    label: Complexity
+    description: Complexity of the command.
+    options:
+    - S (no subcommands, low argument complexity)
+    - M (less than 20 subcommands, medium argument complexity)
+    - L (over 20 subcommands, large argument complexity)
+    - Bottomless Pit (git, aws, gcloud, az, kubectl)
+  validations:
+    required: true
+- type: textarea
+  attributes:
+    label: Anything else?
+    description: |
+      Links? References? Anything that will give us more context about the request!
+
+      Tip: You can attach images or log files by clicking this area to highlight it and then dragging files in.
+  validations:
+    required: false