Make B024 and B027 documentation more nuanced (#11341)

Closes https://github.com/astral-sh/ruff/issues/11334.

crates/ruff_linter/src/rules/flake8_bugbear/rules/abstract_base_class.rs

@@ -14,12 +14,12 @@ use crate::registry::Rule;
 /// Checks for abstract classes without abstract methods.
 ///
 /// ## Why is this bad?
-/// Abstract base classes are used to define interfaces. If they have no abstract
+/// Abstract base classes are used to define interfaces. If an abstract base
-/// methods, they are not useful.
+/// class has no abstract methods, you may have forgotten to add an abstract
+/// method to the class or omitted an `@abstractmethod` decorator.
 ///
-/// If the class is not meant to be used as an interface, it should not be an
+/// If the class is _not_ meant to be used as an interface, consider removing
-/// abstract base class. Remove the `ABC` base class from the class definition,
+/// the `ABC` base class from the class definition.
-/// or add an abstract method to the class.
 ///
 /// ## Example
 /// ```python
@@ -62,11 +62,9 @@ impl Violation for AbstractBaseClassWithoutAbstractMethod {
 /// decorator.
 ///
 /// ## Why is this bad?
-/// Empty methods in abstract base classes without an abstract decorator are
+/// Empty methods in abstract base classes without an abstract decorator may be
-/// indicative of unfinished code or a mistake.
+/// be indicative of a mistake. If the method is meant to be abstract, add an
-///
+/// `@abstractmethod` decorator to the method.
-/// Instead, add an abstract method decorated to indicate that it is abstract,
-/// or implement the method.
 ///
 /// ## Example
 /// ```python