Remove default labels from issue templates

.github/ISSUE_TEMPLATE/bug_report.md

@@ -2,7 +2,7 @@
 name: Bug report
 about: Report incorrect or outdated documentation
 title: ''
-labels: bug
+labels: ''
 assignees: ''
 ---
 

.github/ISSUE_TEMPLATE/enhancement_request.md

@@ -2,7 +2,7 @@
 name: Enhancement request
 about: Suggest new documentation or improving existing documentation
 title: ''
-labels: enhancement
+labels: ''
 assignees: ''
 ---