Add browser bug reporting links to CONTRIBUTING docs; refs twbs#13974

CONTRIBUTING.md

@@ -76,6 +76,18 @@ Example:
 > causing the bug, and potential solutions (and your opinions on their
 > merits).
 
+### Reporting upstream browser bugs
+
+Sometimes bugs reported to us are actually caused by bugs in the browser(s) themselves, not bugs in Bootstrap per se.
+When feasible, we aim to report such upstream bugs to the relevant browser vendor(s), and then list them on our [Wall of Browser Bugs](http://getbootstrap.com/browser-bugs/).
+
+| Vendor(s)     | Browser(s)                   | Rendering engine | Bug reporting website(s)                                                              | Notes                                                    |
+| ------------- | ---------------------------- | ---------------- | ------------------------------------------------------------------------------------- | -------------------------------------------------------- |
+| Mozilla       | Firefox                      | Gecko            | https://bugzilla.mozilla.org/enter_bug.cgi                                            | "Core" is normally the right product option to choose.   |
+| Apple         | Safari                       | WebKit           | https://bugs.webkit.org/enter_bug.cgi?product=WebKit <br> https://bugreport.apple.com | In Apple's bug reporter, choose "Safari" as the product. |
+| Google, Opera | Chrome, Chromium, Opera v15+ | Blink            | https://code.google.com/p/chromium/issues/list                                        | Click the "New issue" button.                            |
+| Microsoft     | Internet Explorer            | Trident          | https://connect.microsoft.com/IE/feedback/LoadSubmitFeedbackForm                      |                                                          |
+
 
 ## Feature requests