created a github issue template [ci skip]

.github/ISSUE_TEMPLATE.md

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+If posting a Strawberry Fields issue, please delete the section above the dashed line, and fill in the template below.
+
+If making a feature request, ignore the following template and describe, in detail, the feature and why it is needed.
+
+For additional support:
+* Check out our documentation: https://strawberryfields.readthedocs.io
+* Join us on our Slack channel: https://join.slack.com/t/sf-xanadu/shared_invite/enQtMzQ0NzA0NTczNTkxLTJhOWM0MzY4N2U1ODc5NWZmY2JlN2FmOTY3OTE3ZmVjMWFhZjMwZWY0ODRkZDFmMTA5NjA1YjgyYzA3NDg3NGM
+
+-----------------------------------------------------------------------------------------------------------------------
+
+#### Issue description
+
+Description of the issue - include code snippets and screenshots if relevant
+
+
+#### Steps to reproduce
+
+1. [First Step]
+2. [Second Step]
+3. [and so on...]
+
+* *Expected behavior:* (What you expect to happen)
+
+* *Actual behavior:* (What actually happens)
+
+* *Reproduces how often:* (What percentage of the time does it reproduce?)
+
+
+#### System information
+
+* *Operating system:*
+  Include the operating system version if you can, e.g. Ubuntu Linux 16.04
+
+
+* *Strawberry Fields version:*
+  This can be found by running
+  ```
+  python -c "import strawberryfields as sf; print(sf.version())"
+  ```
+
+* *Python version:*
+  This can be found by running `python --version`
+
+
+* *NumPy, SciPy, and Tensorflow versions:*
+  These can be found by running
+  ```
+  python -c "import numpy as np; import scipy as sp; import tensorflow as tf; print(np.__version__,sp.__version__,tf.__version__)"
+  ```
+
+* *Installation method:*
+
+  Did you install Strawberry Fields via pip, or directly from the GitHub repository source code?
+
+  If installed via GitHub, what branch/commit did you use? You can get this information by opening a terminal in the
+  Strawberry Fields source code directory, and pasting the output of
+  ```
+  git log -n 1 --pretty=format:"%H%n%an%n%ad%n%s"
+  ```
+
+
+#### Source code and tracebacks
+
+Please include any additional code snippets and error tracebacks related to the issue here.
+
+
+#### Additional information
+
+Any additional information, configuration or data that might be necessary to reproduce the issue.