Typo in trunk's documentation for ``managed`` Meta option

[Tim Valenta]

Point 2 in the list shown here: ​Meta: managed

However, a the intermediary table between one managed and one unmanaged model will be created.

Patch removes "a", resulting in:

However, the intermediary table between one managed and one unmanaged model will be created.

[Tim Valenta]

Removes double article in sentence.

[Tim Graham]

(In [15051]) Fixed #14927 - typo in model option docs. thanks tiliv.

[Tim Graham]

(In [15052]) [1.2.X] Fixed #14927 - typo in model option docs. thanks tiliv.

Backport of r15051 from trunk.