[flake8-builtins] Update documentation (A005) (#16097)

Follow-up to https://github.com/astral-sh/ruff/pull/15951 to update
* the options links in A005 to reference
`lint.flake8-builtins.builtins-strict-checking`
* the description of the rule to explain strict vs non-strict checking
* the option documentation to point back to the rule

crates/ruff_workspace/src/options.rs

@@ -1149,6 +1149,10 @@ pub struct Flake8BuiltinsOptions {
         example = "builtins-strict-checking = false"
     )]
     /// Compare module names instead of full module paths.
+    ///
+    /// Used by [`A005` - `stdlib-module-shadowing`](https://docs.astral.sh/ruff/rules/stdlib-module-shadowing/).
+    ///
+    /// In preview mode the default value is `false` rather than `true`.
     pub builtins_strict_checking: Option<bool>,
 }