This has been asked for on many occasions and avast haven't included as the risk of accidental use could have serious consequences. Avast consider that exclusions should be a deliberate act, so no accidental use. For those that are sent to the virus chest there is a single action (in the later avast versions) to restore and exclude in one action. I'm an avast user not an avast employee, but I do agree with their looking after the less experienced user.
For those that aren't sent to the virus chest, it rather depends on what they are, what your settings are and what the detection is.
THERE IS NO NEED TO SHOUT.