Fix typo in python comment.

Reconstruction/tauRec/python/TauToolHolder.py

@@ -650,7 +650,7 @@ def ImpactPoint3dEstimatorCfg(flags):
     from TrkConfig.AtlasExtrapolatorConfig import AtlasExtrapolatorCfg
     Trk__ImpactPoint3dEstimator = CompFactory.Trk.ImpactPoint3dEstimator
     AtlasExtrapolator = result.popToolsAndMerge(AtlasExtrapolatorCfg(flags))
-    #This is a public took, so we explicitly must add it to the ToolSvc
+    #This is a public tool, so we explicitly must add it to the ToolSvc
     result.addPublicTool(AtlasExtrapolator) 
     TauInDetImpactPoint3dEstimator = Trk__ImpactPoint3dEstimator(name = sPrefix+'TauTrkImpactPoint3dEstimator', Extrapolator = AtlasExtrapolator   )