More doc fixup

python/lsst/cp/pipe/makeBrighterFatterKernel.py

@@ -457,9 +457,10 @@ def _prepareImage(self, exp, gains, level):
         config.nPixBorderXCorr, then rescale by the gain
         and subtract the sigma-clipped mean.
         If the level is 'DETECTOR' then this is done
-        for the whole image in-place so that it can be cross-correlated.
+        to the whole image so that it can be cross-correlated, with a copy
+        being returned.
         If the level is 'AMP' then this is done per-amplifier,
-        and each amp-image returned.
+        and a copy of each prepared amp-image returned.
 
         Parameters:
         -----------
@@ -478,7 +479,7 @@ def _prepareImage(self, exp, gains, level):
 
         Notes:
         ------
-        This function is controlled by the following pexConfig parameters:
+        This function is controlled by the following config parameters:
         nPixBorderXCorr : `int`
             The number of border pixels to exclude
         nSigmaClipXCorr : `float`
@@ -564,7 +565,7 @@ def _crossCorrelate(self, maskedIm0, maskedIm1, frameId=None, detId=None):
 
         Notes:
         ------
-        This function is controlled by the following pexConfig parameters:
+        This function is controlled by the following config parameters:
         maxLag : `int`
             The maximum lag to use in the cross-correlation calculation
         nPixBorderXCorr : `int`