Change example of non-letter in version ordering

[gridbugs]

The "Package Formulas" grammar in the manual says that valid characters for version numbers are <identchar> | "+" | "." | "~". Notably this does not include the "#" character. This change updates the example of a comparing a letter to a non-letter character to use a non-letter character that may appear in a version number.

Please update master_changes.md file with your changes.