Document an example `Makefile` for `coq_makefile`
Document an example `Makefile` for `coq_makefile`

We document an example `Makefile` which does not include the generated
`CoqMakefile`, but instead invokes arbitrary targets in it.

silene/coq,ejgallego/coq,ejgallego/coq,ppedrot/coq,silene/coq,ppedrot/coq,letouzey/coq-wip,ejgallego/coq,ppedrot/coq,gares/coq,JasonGross/coq,silene/coq,Zimmi48/coq,william-lawvere/coq,gares/coq,SkySkimmer/coq,maximedenes/coq,ppedrot/coq,maximedenes/coq,coq/coq,coq/coq,SkySkimmer/coq,Zimmi48/coq,amintimany/coq,maximedenes/coq,Zimmi48/coq,amintimany/coq,SkySkimmer/coq,amintimany/coq,Matafou/coq,maximedenes/coq,JasonGross/coq,maximedenes/coq,ejgallego/coq,coq/coq,JasonGross/coq,letouzey/coq-wip,gares/coq,gares/coq,gares/coq,Matafou/coq,SkySkimmer/coq,Zimmi48/coq,william-lawvere/coq,william-lawvere/coq,JasonGross/coq,coq/coq,Matafou/coq,ppedrot/coq,letouzey/coq-wip,letouzey/coq-wip,letouzey/coq-wip