Update instructions for reimbursement

[hackygolucky]

This includes the Expense Report required to file for reimbursement.

[ChALkeR]

This is a very good change. 👍
I had problems finding out which template I should fill out last year, as I had never done this previously.

[ChALkeR]

A filled-out anonymized example for attending some event would be even better, with all possible expenses listed in (including visa etc).

[hackygolucky]

@ChALkeR mind if I make that a next pull request?

[ChALkeR]

@hackygolucky That would be ideal, thanks!