brew: print help when no commands given
brew: print help when no commands given

Fixes Homebrew/homebrew#49325.

Closes Homebrew/homebrew#49327.

Signed-off-by: Mike McQuaid <a17fed27eaa842282862ff7c1b9c8395a26ac320@mikemcquaid.com>

mgrimes/brew,gregory-nisbet/brew,JCount/brew,konqui/brew,gordonmcshane/homebrew,MikeMcQuaid/brew,DomT4/brew,EricFromCanada/brew,bfontaine/brew,maxim-belkin/brew,alyssais/brew,reitermarkus/brew,reelsense/brew,Linuxbrew/brew,muellermartin/dist,mahori/brew,mistydemeo/homebrew,muellermartin/dist,rwhogg/brew,hanxue/linuxbrew,aw1621107/brew,MikeMcQuaid/brew,konqui/brew,toonetown/homebrew,maxim-belkin/brew,staticfloat/brew,vitorgalvao/brew,mgrimes/brew,Homebrew/brew,bfontaine/brew,Homebrew/brew,amar-laksh/brew_sudo,reitermarkus/brew,palxex/brew,jmsundar/brew,gregory-nisbet/brew,rwhogg/brew,mahori/brew,DomT4/brew,Homebrew/brew,gordonmcshane/homebrew,MikeMcQuaid/brew,jmsundar/brew,mahori/brew,reitermarkus/brew,tonyg/homebrew,sjackman/homebrew,zmwangx/brew,reitermarkus/brew,nandub/brew,jmsundar/brew,palxex/brew,alyssais/brew,nandub/brew,amar-laksh/brew_sudo,zmwangx/brew,vitorgalvao/brew,zmwangx/brew,toonetown/homebrew,Homebrew/brew,gordonmcshane/homebrew,claui/brew,AnastasiaSulyagina/brew,reelsense/brew,pseudocody/brew,konqui/brew,reelsense/brew,hanxue/linuxbrew,hanxue/linuxbrew,palxex/brew,aw1621107/brew,toonetown/homebrew,EricFromCanada/brew,tonyg/homebrew,DomT4/brew,JCount/brew,rwhogg/brew,EricFromCanada/brew,EricFromCanada/brew,claui/brew,nandub/brew,AnastasiaSulyagina/brew,staticfloat/brew,Linuxbrew/brew,muellermartin/dist,Linuxbrew/brew,ilovezfs/brew,ilovezfs/brew,sjackman/homebrew,JCount/brew,mistydemeo/homebrew,DomT4/brew,amar-laksh/brew_sudo,tonyg/homebrew,staticfloat/brew,vitorgalvao/brew,claui/brew,JCount/brew,Linuxbrew/brew,mistydemeo/homebrew,aw1621107/brew,sjackman/homebrew,vitorgalvao/brew,AnastasiaSulyagina/brew,konqui/brew,maxim-belkin/brew,mgrimes/brew,claui/brew,bfontaine/brew,ilovezfs/brew,alyssais/brew,nandub/brew,pseudocody/brew,mahori/brew,sjackman/homebrew,MikeMcQuaid/brew,gregory-nisbet/brew,pseudocody/brew