Bug 867985 - update number of locales

We went from 89 to 80 locales. Amending the text to "over 70" and "more than 90%" is vague enough to be accurate for the foreseeable future even as the specific number fluctuates.

bedrock/mozorg/templates/mozorg/contribute.html

@@ -154,7 +154,7 @@ <h1 class="title">{{ _('<strong>15 years</strong> of a better Web') }}</h1>
           <div class="message">
           <p>
           {% trans %}
-            Our global community has helped translate Firefox into 89 languages, making the browser available to more than 95% of the world's population.
+            Our global community has helped translate Firefox into over 70 languages, making the browser available to more than 90% of the world's population.
           {% endtrans %}
           </p>
           </div>