Add Category Proposal issue template

.github/ISSUE_TEMPLATE/Category_Proposal.md

@@ -0,0 +1,21 @@
+---
+name: Category Proposal
+about: For proposing and discussing a change to the list of categories available under the Elastic Package Specification
+labels: discuss
+title: "[Category Proposal] "
+---
+
+## Context
+
+<!-- Provide some background context on why this new category is needed. -->
+
+## Implementation checklist
+
+<!-- Modifications on categories impact package-spec, but also: package-registry and fleet.
+Keep this list as guide on the implementation of this change
+ -->
+
+- [] Support in package-spec manifest categories
+- [] Support in package-registry /categories API
+- [] Support in Fleet
+- [] Update integrations dependencies to support new category

CONTRIBUTING.md

@@ -29,6 +29,9 @@ something like this:
 5. No single PR may close the proposal issue. But as these PRs get resolved, the corresponding checklist item should be 
    checked off. The proposal issue is closed when all items are checked off.
 
+## Category Proposals
+
+Specific changes regarding categories can please use the [new Category Proposal issue](https://github.com/elastic/package-spec/issues/new/choose).
 
 ## Folder Item spec