Issue template: fix typo (#849)

"enhancementfor" -> "enhancement for"

Author: hugovk

.github/ISSUE_TEMPLATE/bug_report.md

@@ -8,7 +8,7 @@ assignees: ''
 ---
 
 > Note: This repo is for the Python devguide. If you are requesting an
-enhancementfor the Python language or CPython interpreter,
+enhancement for the Python language or CPython interpreter,
 then the CPython issue tracker is better
 suited for this report: https://bugs.python.org