Address Copilot grammar feedback

- pandas: "replace the rest rows" -> "replace the remaining rows"
- pandas_panel: add commas around the introductory phrase / before "as"
  to fix the run-on sentence about groupby axis=1 removal

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: mmcky

lectures/pandas.md

@@ -349,7 +349,7 @@ df.loc[complexCondition]
 The ability to make changes in dataframes is important to generate a clean dataset for future analysis.
 
 
-**1.** We can use `df.where()` conveniently to "keep" the rows we have selected and replace the rest rows with `NaN`
+**1.** We can use `df.where()` conveniently to "keep" the rows we have selected and replace the remaining rows with `NaN`
 
 ```{code-cell} ipython3
 df.where(df.POP >= 20000)

lectures/pandas_panel.md

@@ -401,7 +401,7 @@ plt.show()
 We can also specify a level of the `MultiIndex` (in the column axis)
 to aggregate over. 
 
-In the case of `groupby` we need to use `.T` to transpose the columns into rows as `pandas` has removed support for `axis=1` in the `groupby` method.
+In the case of `groupby`, we need to use `.T` to transpose the columns into rows, as `pandas` has removed support for `axis=1` in the `groupby` method.
 
 ```{code-cell} ipython3
 merged.T.groupby(level='Continent').mean().head()