New developer papercut - Makefile references INSTALL

Hello,

I encountered a minor road bump when checking out the pg source today. The Makefile's all target includes the following help message if GNUmakefile isn't available: 

  echo "You need to run the 'configure' program first. See the file"; \
  echo "'INSTALL' for installation instructions." ; \

After consulting README.git, it looks as though INSTALL isn't created unless the source is bundled into a release or snapshot tarball. I'm happy to submit a patch to update the wording, but wanted to check on the preferred approach.

Perhaps this would be sufficient?

  echo "You need to run the 'configure' program first. See the file"; \
  echo "'INSTALL' for installation instructions, or visit" ; \
  echo "<https://www.postgresql.org/docs/devel/installation.html>" ; \

-Tim