0006 multiple permissive policies - Increase clarity of example, correct final example code

# Improve documentation ## Link [0006 multiple permissive policies](https://supabase.com/docs/guides/database/database-advisors?lint=0006_multiple_permissive_policies) ## Describe the problem In the "How to Resolve" section there are some typos/mismatches between the English text and the code examples, and the final example (the combined policy) does not actually fix the described issue. From top to bottom, I find these could have greater clarity or are not matching some element that follows: > Policy B allows access to employees at or above a certain grade level. ```sql -- Policy B create policy grade_level_access on employee_data for select using (grade_level <= current_user_grade_level()); ``` > Our intention is for users to be able to see employee data for employees within their own department who are **below the querying user's grade level.** Lack of clarity: At or above **_a certain grade level_** -- which grade level? The function name is clear (the current user's grade level) so we should have this text match. Incorrect semantics: **_At or above_** a certain grade level -- Policy B, as written, is allowing access to rows where grade_level is _below or equal to_ the current user's grade level: `grade_level <= current_user_grade_level()`. The code is (almost) in line with the stated intention of "below the querying user's grade level" (should be "at or below"), but the description of Policy B is not. The description should be changed to "at or below" for Policy B, and the intention line should also have "at or" added for all text to be equal. > The implementation contains a logic error. As written, every employee can see `employee_data` for every other employee within their departemnt [sic] Typo: departemnt -> department. Additional clarity: "...every employee can see `employee_data` for _every_ other employee within their department" -- elaborate further on what the difference is between the intended implementation and the actual implementation…