Don't repeat descriptions

[philderbeast]

Don't repeat these descriptions between dhall2stack and dhall2cabal text templates.

# Source Packages, external (3rd party).

# Source Packages, internal to this organisation (private and public).

# Source Packages, external (3rd party) forks of other repositories.
# Can we help upstream?

# Source Packages, internal forks of other repositories.
# Can we upstream and unfork?

# Package versions for published packages either not on Stackage or
# not matching the version on Stackage for the resolver we use.
# These package-version extra dependencies are equivalent to cabal constraints.