message: Fix invalid title on search results page
diff: {%- extends "base.html" -%}
  {%- import "releases/header.html" as release_macros -%}
  -{%- block title -%}Releases - Docs.rs{%- endblock title -%}
  +{%- block title -%}{{ title | default(value="Releases - Docs.rs")}}{%- endblock title -%}
  {%- block header -%}
  {# These all have defaults so searches work #}
  