Remove hyperbolic tone from SQL guideline on pluck

The statement "Never use" is already sufficiently clear and does not
need to be prefixed with another level of hyperbole. It makes me
uncomfortable when I link people to this line of the docs since it feels
like such a hostile way to give someone feedback. We can remove the
passion from these docs and still convey the same importance.

doc/development/sql.md

@@ -218,9 +218,9 @@ Project.select(:id, :user_id).joins(:merge_requests)
 
 ## Plucking IDs
 
-This can't be stressed enough: **never** use ActiveRecord's `pluck` to pluck a
-set of values into memory only to use them as an argument for another query. For
-example, this will make the database **very** sad:
+Never use ActiveRecord's `pluck` to pluck a set of values into memory only to
+use them as an argument for another query. For example, this will execute an
+extra unecessary database query and load a lot of unecessary data into memory:
 
 ```ruby
 projects = Project.all.pluck(:id)