Give more guarntees about ImplicitParams (#23289)

Added new points into description of ImplicitParams into GHC user's guide to fix the #23289 (closed) issue.

• ensure that your commits are either individually buildable or squashed
• ensure that your commit messages describe what they do (referring to tickets using #NNNN syntax when appropriate)
• add a [testcase to the testsuite][adding test].
• updates the users guide if applicable