fix: update layout and import Chirpy template files

_includes/post-description.html

@@ -0,0 +1,16 @@
+{%- comment -%}
+  Get post description or generate it from the post content.
+{%- endcomment -%}
+
+{%- assign max_length = include.max_length | default: 200 -%}
+
+{%- capture description -%}
+{%- if post.description -%}
+  {{- post.description -}}
+{%- else -%}
+  {%- include no-linenos.html content=post.content -%}
+  {{- content | markdownify | strip_html -}}
+{%- endif -%}
+{%- endcapture -%}
+
+{{- description | strip | truncate: max_length | escape -}}