Added documentation for ActiveRecord::Relation#pick [skip ci]

- Add nuances of the primarily useful cases to the code examples
- Changed description to use some wording from API docs

guides/source/active_record_querying.md

@@ -2256,6 +2256,25 @@ irb> assoc.unscope(:includes).pluck(:id)
 
 [`pluck`]: https://api.rubyonrails.org/classes/ActiveRecord/Calculations.html#method-i-pluck
 
+### `pick`
+
+[`pick`][] can be used to pick the value(s) from the named column(s) in the current relation. It accepts a list of column names as an argument and returns the first row of the specified column values ​​with corresponding data type.
+`pick` is an short-hand for `relation.limit(1).pluck(*column_names).first`, which is primarily useful when you already have a relation that is limited to one row.
+
+`pick` makes it possible to replace code like:
+
+```ruby
+Customer.where(id: 1).pluck(:id).first
+```
+
+with:
+
+```ruby
+Customer.where(id: 1).pick(:id)
+```
+
+[`pick`]: https://api.rubyonrails.org/classes/ActiveRecord/Calculations.html#method-i-pick
+
 ### `ids`
 
 [`ids`][] can be used to pluck all the IDs for the relation using the table's primary key.