docs: Fix a few typos

[timgates42]

There are small typos in:

• src/conf.py
• src/correctness/no_exception_type_specified.rst
• src/django/1.8/migration/index.rst
• src/django/all/security/index.rst
• src/performance/not_using_iteritems_to_iterate_large_dict.rst
• src/readability/not_using_a_dict_comprehension.rst
• src/readability/not_using_dict_keys_when_formatting_strings.rst
• src/readability/putting_type_information_in_a_variable_name.rst

Fixes:

• Should read reduce rather than recude.
• Should read proprietary rather than proprietory.
• Should read preferred rather than prefered.
• Should read paths rather than pathes.
• Should read package rather than packafe.
• Should read occurred rather than occured.
• Should read modified rather than modifed.
• Should read installs rather than installes.
• Should read explicitly rather than explicity.
• Should read comprehension rather than comprehesion.

Semi-automated pull request generated by https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md