doc: Cleanup Makefile
doc: Cleanup Makefile

Since make already runs all the commands in 'set -e' style,
we can drop the && concatenation of shell commands and make
everything a bit simpler.

Closes #5834

xhad/cockpit,mareklibra/cockpit,xhad/cockpit,mvollmer/cockpit,stefwalter/cockpit,cockpituous/cockpit,dperpeet/cockpit,andreasn/cockpit,andreasn/cockpit,larsu/cockpit,garrett/cockpit,larsu/cockpit,andreasn/cockpit,petervo/cockpit,stefwalter/cockpit,dperpeet/cockpit,mareklibra/cockpit,cockpituous/cockpit,mvollmer/cockpit,michalskrivanek/cockpit,mareklibra/cockpit,larskarlitski/cockpit,petervo/cockpit,Scribery/cockpit,cockpituous/cockpit,michalskrivanek/cockpit,xhad/cockpit,petervo/cockpit,stefwalter/cockpit,moraleslazaro/cockpit,Scribery/cockpit,Scribery/cockpit,martinpitt/cockpit,mareklibra/cockpit,moraleslazaro/cockpit,dperpeet/cockpit,mvollmer/cockpit,xhad/cockpit,moraleslazaro/cockpit,michalskrivanek/cockpit,deryni/cockpit,larsu/cockpit,cockpit-project/cockpit,Scribery/cockpit,andreasn/cockpit,mvollmer/cockpit,harishanand95/cockpit,petervo/cockpit,andreasn/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,larskarlitski/cockpit,dperpeet/cockpit,cockpituous/cockpit,martinpitt/cockpit,michalskrivanek/cockpit,moraleslazaro/cockpit,Scribery/cockpit,moraleslazaro/cockpit,harishanand95/cockpit,xhad/cockpit,martinpitt/cockpit,martinpitt/cockpit,stefwalter/cockpit,mareklibra/cockpit,dperpeet/cockpit,larsu/cockpit,garrett/cockpit,cockpituous/cockpit,harishanand95/cockpit,larskarlitski/cockpit,larsu/cockpit,SotolitoLabs/cockpit,larskarlitski/cockpit,larsu/cockpit,deryni/cockpit,harishanand95/cockpit,deryni/cockpit,stefwalter/cockpit,xhad/cockpit,larskarlitski/cockpit,deryni/cockpit,Scribery/cockpit,andreasn/cockpit,SotolitoLabs/cockpit,petervo/cockpit,cockpit-project/cockpit,dperpeet/cockpit,larskarlitski/cockpit,garrett/cockpit,andreasn/cockpit,mareklibra/cockpit,dperpeet/cockpit,stefwalter/cockpit,cockpituous/cockpit,michalskrivanek/cockpit,garrett/cockpit,SotolitoLabs/cockpit,harishanand95/cockpit,michalskrivanek/cockpit,Scribery/cockpit,xhad/cockpit,moraleslazaro/cockpit,stefwalter/cockpit,SotolitoLabs/cockpit,deryni/cockpit,harishanand95/cockpit,harishanand95/cockpit,SotolitoLabs/cockpit,deryni/cockpit,cockpit-project/cockpit,petervo/cockpit,garrett/cockpit,deryni/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,michalskrivanek/cockpit,martinpitt/cockpit,cockpit-project/cockpit,larskarlitski/cockpit,SotolitoLabs/cockpit,petervo/cockpit