fix typo practise -> practice

[fzakaria]

A few typo errors for practice are fixed. They occur in documentation when referring to bestpractice module and in general.

[rogerbinns]

I am British and this is relevant: https://www.grammarly.com/blog/practice-practise/

I did deliberately ensure that the module name took American English spelling to avoid confusion. But everywhere else I am using British English.