CHANGES.md checks in CI are insufficient for the desired level of pedantry

[bob-beck]

The checks for CHANGES.md in CI do not catch basic formatting pedantry that appears to be desired.

For example, some folks care about the number of leading spaces in a CHANGES.md file.

As none of these requirements are actually documented anywhere, the CHANGES.md checks in
ci should catch these things so that they can be fixed not by wasting the limited processing power of
meatspace entities on mindless pedantry better done by a computer.

[hesam-oxe]

@bob-beck @t8m

I can add the CI checks for CHANGES.md formatting.

I'll add a linter/checker that validates:

• Consistent leading spaces
• Proper entry format
• Common formatting mistakes that currently waste human review time

This way the CI catches the pedantry before it reaches meatspace entities. 😄

/assign