Allow raw string literals and add a sample usage.

styleguide/c++/c++11.html

Index: styleguide/c++/c++11.html
diff --git a/styleguide/c++/c++11.html b/styleguide/c++/c++11.html
index 8e1a3f25f0ed45cfca3569fced6742e30f3977b6..b9dffc10a11c55b1a9bf581cfef3f403309eb60a 100644
--- a/styleguide/c++/c++11.html
+++ b/styleguide/c++/c++11.html
@@ -682,7 +682,7 @@ work in all our compilers yet.</p>
 <td><code>string <i>var</i>=R&quot;(<i>raw_string</i>)&quot;;</code></td>
 <td>Allows a string to be encoded without any escape sequences, easing parsing in regex expressions, for example</td>
 <td><a href="http://en.cppreference.com/w/cpp/language/string_literal">string literal</a></td>
-<td>Causes incorrect line numbers in MSVS2013 and gcc. Reevaluate once that works. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/2kWQHbbuMHI">Discussion thread</a></td>
+<td>Beware of passing these as macro arguments, which can trigger a <a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57824">lexer bug</a> on older GCC versions. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/2kWQHbbuMHI">Discussion thread</a></td>
 </tr>
 
 <tr>