[pango] Document the break testcase

[Matthias Clasen <matthiasc src gnome org>]

commit 901b59f4517e042081df0838326785903ecec2df
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jul 7 21:19:02 2019 -0400

    Document the break testcase

 tests/breaks/one.break | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/tests/breaks/one.break b/tests/breaks/one.break
index f30dc534..75310e8c 100644
--- a/tests/breaks/one.break
+++ b/tests/breaks/one.break
@@ -1 +1,2 @@
+# Test breaks around /, soft hyphen, and space.
 abc/def ghi­jkl. Bla