DOC: Fix versionadded directive typos in IntervalIndex (#21649)

(cherry picked from commit b35cb1c)

Author: jschendel

pandas/core/indexes/interval.py

@@ -160,7 +160,7 @@ class IntervalIndex(IntervalMixin, Index):
     dtype : dtype or None, default None
         If None, dtype will be inferred
 
-        ..versionadded:: 0.23.0
+        .. versionadded:: 0.23.0
 
     Attributes
     ----------
@@ -438,7 +438,7 @@ def from_breaks(cls, breaks, closed='right', name=None, copy=False,
         dtype : dtype or None, default None
             If None, dtype will be inferred
 
-            ..versionadded:: 0.23.0
+            .. versionadded:: 0.23.0
 
         Examples
         --------
@@ -568,7 +568,7 @@ def from_intervals(cls, data, closed=None, name=None, copy=False,
         dtype : dtype or None, default None
             If None, dtype will be inferred
 
-            ..versionadded:: 0.23.0
+            .. versionadded:: 0.23.0
 
         Examples
         --------
@@ -619,7 +619,7 @@ def from_tuples(cls, data, closed='right', name=None, copy=False,
         dtype : dtype or None, default None
             If None, dtype will be inferred
 
-            ..versionadded:: 0.23.0
+            .. versionadded:: 0.23.0
 
         Examples
         --------
@@ -671,7 +671,7 @@ def to_tuples(self, na_tuple=True):
             Returns NA as a tuple if True, ``(nan, nan)``, or just as the NA
             value itself if False, ``nan``.
 
-            ..versionadded:: 0.23.0
+            .. versionadded:: 0.23.0
 
         Examples
         --------