DOC: update docs to reflect new mode.use_inf_as_null option

Author: y-p

RELEASE.rst

@@ -99,7 +99,7 @@ pandas 0.10.0
     instead. This is a legacy hack and can lead to subtle bugs.
   - inf/-inf are no longer considered as NA by isnull/notnull. To be clear, this
     is legacy cruft from early pandas. This behavior can be globally re-enabled
-    using pandas.core.common.use_inf_as_na (#2050, #1919)
+    using the new option ``mode.use_inf_as_null`` (#2050, #1919)
   - ``pandas.merge`` will now default to ``sort=False``. For many use cases
     sorting the join keys is not necessary, and doing it by default is wasteful
   - ``names`` handling in file parsing: if explicit column `names` passed,

doc/source/missing_data.rst

@@ -61,7 +61,7 @@ arise and we wish to also consider that "missing" or "null".
 
 Until recently, for legacy reasons ``inf`` and ``-inf`` were also
 considered to be "null" in computations. This is no longer the case by
-default; use the :func: `~pandas.core.common.use_inf_as_null` function to recover it.
+default; use the ``mode.use_inf_as_null`` option to recover it.
 
 .. _missing.isnull: