Unify all "/releases" pages to be "centered"

Author: GuillaumeGomez

crates/bin/docs_rs_web/templates/releases/activity.html

@@ -12,6 +12,10 @@
     {%- include "header/topbar.html" -%}
 {%- endblock topbar -%}
 
+{%- block body_classes -%}
+centered
+{%- endblock body_classes -%}
+
 {%- block body -%}
     <div class="container">
         <canvas id="releases-activity-chart"></canvas>

crates/bin/docs_rs_web/templates/releases/build_queue.html

@@ -12,6 +12,10 @@
     {%- include "header/topbar.html" -%}
 {%- endblock topbar -%}
 
+{%- block body_classes -%}
+centered
+{%- endblock body_classes -%}
+
 {%- block body -%}
     <div class="container">
         <div class="recent-releases-container">