bpo-29520: doc: add missing dot (GH-182)

3eea8c6 missed dot at the end of paragraph.
diff --git a/Doc/tools/templates/indexcontent.html b/Doc/tools/templates/indexcontent.html
index 2bf2cce..d795c0a 100644
--- a/Doc/tools/templates/indexcontent.html
+++ b/Doc/tools/templates/indexcontent.html
@@ -5,7 +5,7 @@
 {% block body %}
   <h1>{{ docstitle|e }}</h1>
   <p>
-  {% trans %}Welcome! This is the documentation for Python {{ release }}{% endtrans %}
+  {% trans %}Welcome! This is the documentation for Python {{ release }}.{% endtrans %}
   </p>
   <p><strong>{% trans %}Parts of the documentation:{% endtrans %}</strong></p>
   <table class="contentstable" align="center"><tr>