[css-tables-3] Fix errors in border conflict resolution

This change fixes row-separator border conflict resolution; the "separates two
rows" block incorrectly referenced table-column and table-column-group instead
of table-row and table-row-group.

[Chrome's
impl](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/layout/table/table_borders.cc;l=433-503;drc=8c0301b5c76ca4d7e7ae01daa9bfe3bc5fe697a4), [Firefox's
impl](https://searchfox.org/firefox-main/source/layout/tables/nsTableFrame.cpp#4794-5418)

Author: keithamus

css-tables-3/Overview.bs

@@ -1320,10 +1320,10 @@ spec:css-display-4; type:property; text:display
 				<ul>
 					<li>For each border BC<sub>i</sub>:
 						For each table-row spanned by the C<sub>i</sub> cell, if any.
-						Consider the border&#8217;s properties of any border of the table-column that would be drawn contiguously to BC<sub>i</sub>.
+						Consider the border&#8217;s properties of any border of the table-row that would be drawn contiguously to BC<sub>i</sub>.
 
 					<li>For each border BC<sub>i</sub>:
-						For each table-row-group containing a column spanned by the C<sub>i</sub> cell, if any.
+						For each table-row-group containing a row spanned by the C<sub>i</sub> cell, if any.
 						Consider the border&#8217;s properties of any border of the table-row-group that would be drawn contiguously to BC<sub>i</sub>.
 				</ul>