[#171,#229][Crum/Flashcards] Add a Line Break between Meaning and Crum.

This is obviously related to #171, but you might be wondering how it has
anything to do with #229.
The answer is that, with the current HTML, some text extractors see
"Crum" and whatever precedes it as a single word, thus messing up with
our search function (and also with text highlighting experience in the
browser). Adding a line break is a way to ensure that this doesn't
happen.

flashcards/constants.py

@@ -225,6 +225,7 @@ def _explanatory_alt(path: str) -> str:
                     greek,
                     roots_col("en-parsed", line_br=True, force=False),
                 ),
+                "<br/>",
                 # Dictionary pages.
                 field.cat(
                     '<span class="right">',