Tweak CONTRIBUTING.md - mention INSTALL.md *early*
Tweak CONTRIBUTING.md - mention INSTALL.md *early*

  We want people to *quickly* discover how to install the program
  (if they want to).

Signed-off-by: David A. Wheeler <9ae72d22d8b894b865a7a496af4fab6320e6abb2@dwheeler.com>

wanganyv/cii-best-practices-badge,dwvisser/cii-best-practices-badge,coreinfrastructure/best-practices-badge,taylorcoursey/cii-best-practices-badge,taylorcoursey/cii-best-practices-badge,dwvisser/cii-best-practices-badge,linuxfoundation/cii-best-practices-badge,coreinfrastructure/best-practices-badge,dwvisser/cii-best-practices-badge,yannickmoy/cii-best-practices-badge,linuxfoundation/cii-best-practices-badge,linuxfoundation/cii-best-practices-badge,jdossett/cii-best-practices-badge,jdossett/cii-best-practices-badge,yannickmoy/cii-best-practices-badge,jdossett/cii-best-practices-badge,yannickmoy/cii-best-practices-badge,taylorcoursey/cii-best-practices-badge,wanganyv/cii-best-practices-badge,wanganyv/cii-best-practices-badge,linuxfoundation/cii-best-practices-badge,yannickmoy/cii-best-practices-badge,coreinfrastructure/best-practices-badge,taylorcoursey/cii-best-practices-badge,jdossett/cii-best-practices-badge,coreinfrastructure/best-practices-badge,dwvisser/cii-best-practices-badge,wanganyv/cii-best-practices-badge