Fixed spelling errors in documentation.

By default, Django will try to optimize the operations in your migrations

to reduce the size of the resulting file. Pass ``--no-optimize`` if this

process is failing for you or creating incorrect migrations, though please

also file a Django bug report about the behaviour, as optimization is meant

also file a Django bug report about the behavior, as optimization is meant

to be safe.

sqlindexes

sqlmigrate

sqlsequencereset

squashmigrations

ssi

stacktrace

startswith

Unreviewed

unsanitized

unsets

unsquashed

untar

url

urlencode

--------------------

You are encouraged to make migrations freely and not worry about how many you

have; the migration code is optimised to deal with hundreds at a time without

have; the migration code is optimized to deal with hundreds at a time without

much slowdown. However, eventually you will want to move back from having

several hundred migrations to just a few, and that's where squashing comes in.

.. versionchanged:: 1.7

    Previously, you could only simulate the deletion of a setting which was

    explicitely overridden.

    explicitly overridden.

When overriding settings, make sure to handle the cases in which your app's

code uses a cache or similar feature that retains state even if the setting is