Sentence restructured in compare methods's doc (#58708)

* There was a typo in user_guide doc ,particulary in documentation of merge,join ,concatenate and compare
which after fixing is more grmatically correct and making more sense now

* A sentence from section Merge,join,concatenate and compare in user guide doc -specifically in compare method's  docs,
has been restructured so that it is more easy to comprehend ,earlier more obscure sentence has now been simplified by just adding few words more

doc/source/user_guide/merging.rst

@@ -1073,7 +1073,7 @@ compare two :class:`DataFrame` or :class:`Series`, respectively, and summarize t
    df.compare(df2)
 
 By default, if two corresponding values are equal, they will be shown as ``NaN``.
-Furthermore, if all values in an entire row / column, the row / column will be
+Furthermore, if all values in an entire row / column are equal, that row / column will be
 omitted from the result. The remaining differences will be aligned on columns.
 
 Stack the differences on rows.