caveats: tweak keg-only messaging.
caveats: tweak keg-only messaging.

Slim down the existing text and make it more obvious what's happening.
Note specifically how to add it to your PATH to convince people to try
that instead of `brew link --force`.

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