Explicitly state to enable verbose mode

.github/ISSUE_TEMPLATE.md

@@ -19,6 +19,7 @@ Make sure you have checked all steps below.
 - [ ] C Compiler information (e.g. gcc 7.3): 
 - [ ] Please attach a debug trace log as gist
   * If the problem happens in a Pyenv invocation, you can turn on debug logging by setting `PYENV_DEBUG=1`, e.g. `env PYENV_DEBUG=1 pyenv install -v 3.6.4`
+    * If the problem is with `pyenv install`, make sure to also enable its verbose mode (`-v`)
   * If the problem happens outside of a Pyenv invocation, get the debug log like this:
      ```
      export PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'