Add feature request template

Author: lalitrolaniya

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,18 @@
+---
+name: Feature Request
+about: Suggest a new function or improvement
+title: '[FEATURE] '
+labels: enhancement
+---
+
+**Describe the feature**
+What new function or improvement would you like?
+
+**Use case**
+How would this help your research?
+
+**References**
+Any papers or formulas this should be based on?
+
+**Additional context**
+Any other information or screenshots.