Revert "Add more localized strings" (readthedocs#961)

The alt attribute is only valid on the <area>, <img>, and <input>
elements, not <a>.

https://html.spec.whatwg.org/multipage/indices.html#attributes-3:attr-area-alt

This reverts commit 8f32736 (readthedocs#806).

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

sphinx_rtd_theme/layout.html

@@ -118,7 +118,7 @@
           {% if logo and theme_logo_only %}
             <a href="{{ pathto(master_doc) }}">
           {% else %}
-            <a href="{{ pathto(master_doc) }}" class="icon icon-home" alt="{{ _("Documentation Home") }}"> {{ project }}
+            <a href="{{ pathto(master_doc) }}" class="icon icon-home"> {{ project }}
           {% endif %}
 
           {% if logo %}