Use proper formatting for docstring (#1432)

* Use proper formatting for docstring

* Update _next_gen.py

Co-authored-by: 🇺🇦 Sviatoslav Sydorenko (Святослав Сидоренко) <wk.cvs.github@sydorenko.org.ua>

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Co-authored-by: 🇺🇦 Sviatoslav Sydorenko (Святослав Сидоренко) <wk.cvs.github@sydorenko.org.ua>

Author: A5rocks

src/attr/_next_gen.py

@@ -76,7 +76,7 @@ def define(
             sensible ``__ne__`` by default, so it *should* be enough to only
             implement ``__eq__`` in most cases).
 
-            Passing True or False` to *init*, *repr*, *eq*, or *hash*
+            Passing :data:`True` or :data:`False` to *init*, *repr*, *eq*, or *hash*
             overrides whatever *auto_detect* would determine.
 
         auto_exc (bool):