Update and rename Enhancement to enhancement_request.md

Author: MMelQin

.github/ISSUE_TEMPLATE/Enhancement renamed to .github/ISSUE_TEMPLATE/enhancement_request.md

@@ -1,3 +1,12 @@
+---
+name: Enhancement request
+about: Suggest enhancements on specific implementation of MONAI Deploy App SDK and example applications
+title: "[IMP] "
+labels: enhancement
+assignees: ''
+
+---
+
 **Is your enhancemnet request related to a problem? Please describe.**
 <!--
 A clear and concise description of what the enhancement needs to be. Ex. The example app can be improved to show me how to [...]