Replace {{ .Title }} with fixed string

I wanted to generate "Blog posts" instead of "Blog" as h1 on list pages
in the /blog/ namespace. Changing the title in content/blog/_index.md
would have much more effects, so I dediced to make the change here to
only get exactly that one thing changed.

layouts/blog/list.html

@@ -8,7 +8,7 @@
 <header class="page-header">
   {{- partial "breadcrumbs.html" . }}
   <h1>
-    {{ .Title }}
+    Blog posts
     {{- if and (or (eq .Kind `term`) (eq .Kind `section`)) (.Param "ShowRssButtonInSectionTermList") }}
     {{- with .OutputFormats.Get "rss" }}
     <a href="{{ .RelPermalink }}" title="RSS feed of this blog" aria-label="RSS">