New issue template for documentation improvements (#3525)

Signed-off-by: Juan Luis Cano Rodríguez <juan_luis_cano@mckinsey.com>

.github/ISSUE_TEMPLATE/doc-improvement.md

@@ -0,0 +1,14 @@
+---
+name: Documentation improvement
+about: If something could be clarified or added to the docs
+labels: 'Component: Documentation'
+
+---
+
+## Description
+<!-- Short description of the improvement suggestion. -->
+
+## Context
+<!-- Extra context. -->
+
+* Documentation page (if applicable): <!-- https://docs.kedro.org/en/stable/... -->