More clear documentation for "Entry Points"

[Archmonger]

The current docs for entry points are a bit ambiguous about whether the example key should be user defined.

For example, with the metadata/#cli docs:

[project.scripts]
cli-name = "pkg.subpkg:func"

At first glance, it appears that cli-name is an actual toml attribute, rather than a user defined value. This can be resolved by using one or more of the following methods:

1. Change cli-name to example-cli-name to give slightly more clear intent
2. Add a sentence before each example saying Substitute "cli-name" with the namespace you wish to call via command line.
3. Have every example for within the Entry Points section use at least two commands to demonstrate intent

   [project.scripts]
   cli-name1 = "pkg.subpkg1:func"
   cli-name2 = "pkg.subpkg2:func"