chore: update experiments and deprecation docs (#1315)

docs/docs/experiments/template.md

@@ -0,0 +1,20 @@
+---
+# This is a template for an experiments documentation
+# Copy this page and fill in the details as necessary
+title: '--- Template ---'
+sidebar_position: -1 # Always push to the top
+draft: true # Hide in production
+---
+
+# {Name of Experiment}
+
+- Issue: [#{issue}](https://github.com/go-task/task/issues/{issue})
+- Environment variable: `TASK_X_{feature}`
+- Breaks:
+  - {list any existing functionality that will be broken by this experiment}
+- Deprecations:
+  - {link to any deprecation pages related to this experiment}
+
+{Short description of the feature}
+
+{Short explanation of how users should migrate to the new behavior}