[tab:container.hash.req] Add a line break before next itemdecl clause.

Partially addresses #4228.

Author: Dawn Perchik

source/containers.tex

@@ -2788,7 +2788,7 @@
 \indexunordmem{clear}%
 \tcode{a.clear()}
 & \tcode{void}
-& \effects Erases all elements in the container.
+& \effects Erases all elements in the container.\br
    \ensures \tcode{a.empty()} is \tcode{true}%
 & Linear in \tcode{a.size()}.
 \\ \rowsep
@@ -2881,7 +2881,7 @@
 &
   \expects \tcode{b.bucket_count() > 0}.\br
     \returns The index of the bucket in which elements with keys equivalent
-    to \tcode{k} would be found, if any such element existed.
+    to \tcode{k} would be found, if any such element existed.\br
     \ensures The return value shall be in the range \tcode{[0, b.bucket_count())}.%
 & Constant
 \\ \rowsep