Missing colon in documentation

[tonyhallett]

Error template in docs is missing colon in two places.

Actual behavior

[error] Variables named after %s are not allowed!

and

[error] Variables named after %s are not allowed: '%s'

Expected behavior

[error]: Variables named after %s are not allowed!

and

[error]: Variables named after %s are not allowed: '%s'

[JoshuaKGoldberg]

🤖 Beep boop! 👉 TSLint is deprecated 👈 and you should switch to typescript-eslint! 🤖

🔒 This issue is being locked to prevent further unnecessary discussions. Thank you! 👋