You can use addvote command to add custom vote commands to your server. For example, suppose you want your players to be able to vote whether they want bots or not. This can be achieved using the following code:
alias bots "minplayers 4"addvote botsalias nobots "minplayers 0"addvote nobots
Now players will be able to type vcall bots or vcall nobots which will start a vote to have those commands issued.
You can prefix the contents of an alias with settemp to make it be valid only for the current game. For example alias nobots "settemp minplayers 0".
Here's example that allows voting common server types assuming your server.cfg doesn't force them: