Add Wall of Browser Bugs entry for #19670 for Firefox (#20036)

See https://bugzil.la/1278000
Refs #19670

[skip sauce]

docs/_data/browser-bugs.yml

@@ -118,6 +118,16 @@
   origin: >
     Bootstrap#19839
 
+-
+  browser: >
+    Firefox
+  summary: >
+    Mouse sometimes not within element for purposes of `mouseenter`/`mouseleave` when it's within SVG elements
+  upstream_bug: >
+    Mozilla#1278000
+  origin: >
+    Bootstrap#19670
+
 -
   browser: >
     Firefox (Windows)