template for github issue/bug report

[YingzhiGou]

in order to make issue/bug reporting more effectively on GitHub. I suggest we use a template for create issues where there are marked sections to guide reporter to provide necessary information for developers to identify and reproduce the bug. the template below is the one used in matplotlib repo which could be the template of our template.

<!--To help us understand and resolve your issue, please fill out the form to the best of your ability.-->
<!--You can feel free to delete the sections that do not apply.-->

### Bug report

**Bug summary**

<!--A short 1-2 sentences that succinctly describes the bug-->

**Code for reproduction**

<!--A minimum code snippet required to reproduce the bug, also minimizing the number of dependencies required-->

```python
# Paste your code here
#
#
```

**Actual outcome**

<!--The output produced by the above code, which may be a screenshot, console output, etc.-->

```
# If applicable, paste the console output here
#
#
```

**Expected outcome**

<!--A description of the expected outcome from the code snippet-->
<!--If this used to work in an earlier version of Matplotlib, please note the version it used to work on-->

**Matplotlib version**
<!--Please specify your platform and versions of the relevant libraries you are using:-->
  * Operating system:
  * Matplotlib version: 
  * Matplotlib backend (`print(matplotlib.get_backend())`):
  * Python version:
  * Jupyter version (if applicable):
  * Other libraries: 

<!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda-->
<!--If you installed from conda, please specify which channel you used if not the default-->

[YingzhiGou]

these templates are added to the git repo