fix typo

maps/README.rst

@@ -110,7 +110,7 @@ Map Frames and Pipelines
 
 Maps and associated weights are generally stored in memory and on disk in ``G3Frames`` of type ``G3FrameType.Map``, with keys ``'T', 'Q', 'U', 'Wpol'`` defined for polarized maps, and ``'T', 'Wunpol'`` defined for unpolarized maps.  Map frames can be checked for validity using the ``ValidateFrames`` pipeline module, which raises errors or warnings for missing keys or inconsistent attributes.
 
-Map frames can be manipulated in a pipeline using some memory-efficient pipeline modules.  Weights can be applied or removed from their corresponding Stokes maps using the ``ApplyWeights`` or ``RemoveWeights`` pipeline modules.  Maps can be converted to polarized or unpolarized versions using the ``MakeMapPolarized`` and ``MakeMapUnpolarized`` modules.  They can also be compactified to their most sparse representation using the ``CompactMaps`` module.
+Map frames can be manipulated in a pipeline using some memory-efficient pipeline modules.  Weights can be applied or removed from their corresponding Stokes maps using the ``ApplyWeights`` or ``RemoveWeights`` pipeline modules.  Maps can be converted to polarized or unpolarized versions using the ``MakeMapsPolarized`` and ``MakeMapsUnpolarized`` modules.  They can also be compactified to their most sparse representation using the ``CompactMaps`` module.
 
 Existing maps can be injected into a pipeline using the ``InjectMaps`` module, and map stubs can be injected using ``InjectMapStub`` or ``ReplicateMaps``.  Maps can also be extracted from a pipeline using the ``ExtractMaps`` module.