apply consistent language to specify square brackets

Author: nkasing

doc/source/getting_started/intro_tutorials/03_subset_data.rst

@@ -101,7 +101,7 @@ selection brackets ``[]``.
 .. note::
     The inner square brackets define a
     :ref:`Python list <python:tut-morelists>` with column names, whereas
-    the outer brackets are used to select the data from a pandas
+    the outer square brackets are used to select the data from a pandas
     ``DataFrame`` as seen in the previous example.
 
 The returned data type is a pandas DataFrame:
@@ -354,7 +354,7 @@ See the user guide section on :ref:`different choices for indexing <indexing.cho
         <h4>REMEMBER</h4>
 
 -  When selecting subsets of data, square brackets ``[]`` are used.
--  Inside these brackets, you can use a single column/row label, a list
+-  Inside these square brackets, you can use a single column/row label, a list
    of column/row labels, a slice of labels, a conditional expression or
    a colon.
 -  Select specific rows and/or columns using ``loc`` when using the row

doc/source/getting_started/intro_tutorials/05_add_columns.rst

@@ -51,7 +51,7 @@ hPa, the conversion factor is 1.882*)
     air_quality["london_mg_per_cubic"] = air_quality["station_london"] * 1.882
     air_quality.head()
 
-To create a new column, use the ``[]`` brackets with the new column name
+To create a new column, use the square brackets ``[]`` with the new column name
 at the left side of the assignment.
 
 .. raw:: html

doc/source/getting_started/intro_tutorials/06_calculate_statistics.rst

@@ -162,7 +162,7 @@ columns by passing ``numeric_only=True``:
 
 It does not make much sense to get the average value of the ``Pclass``.
 If we are only interested in the average age for each gender, the
-selection of columns (rectangular brackets ``[]`` as usual) is supported
+selection of columns (square brackets ``[]`` as usual) is supported
 on the grouped data as well:
 
 .. ipython:: python