Adding docs for temp issues

Change-Id: I6525f49df91d5cb031a49b0c5b1bc6413b9e81d9

docs/temp.md

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+Predictable temporary path
+=====================
+Creating a temporary file on disk is a common practice, however it has the
+potential to be a source of problems. Naively creating such files using the
+system wide ``/tmp`` folder for example, may result in predictable and
+unprotected file paths. This could allow an attacker to anticipate where
+temporary files will be found and to read or modify them. Manipulation of
+temporary files can result in the ability to control, deny or damage a process
+or system, or gain access to sensitive information. Please see [0] for more
+details.
+
+### Correct
+```python
+import tempfile
+tmp = tempfile.mkstemp()
+```
+
+### Incorrect
+```python
+tmp = open('/tmp/my-tmp-file')
+tmp = open(tempfile.mktemp(), "w")
+```
+
+## Consequences
+* Unintended control of processes or systems
+* Unintended destruction or denial of services
+* Data theft or leakage
+
+## References
+* [0] https://security.openstack.org/guidelines/dg_using-temporary-files-securely.html