fix bug: default show comments. And allow a post or about page to disable comments, just edit front-matter in markdown file:

- disable disabledisqus: Add a line ` disabledisqus = "true" ` in front-matter

    For example:

    ```
    title = "How To Vertically Middle Align Floated Elements With Flexbox"
    description = "How To Vertically Middle Align Floated Elements With Flexbox"
    date = 2017-07-28T20:53:14+08:00
    tags = ["CSS"]
    categories = ["CSS"]
    draft = false
    disabledisqus = "true"
    ```

    The code of this feature will update in future, because the implementation is not so good.

layouts/_default/single.html

@@ -40,13 +40,13 @@
             {{ end }}
 
             {{ if .Site.Params.enableDisqus }}
-                {{ if eq .Params.disabledisqus "true" }}
+                {{ if ne .Params.disabledisqus "true" }}
                     {{ partial "disqus.html" . }}
                 {{ end }}
             {{ end }}
 
             {{ if .Site.Params.enableDuoshuo }}
-                {{ if eq .Params.disableduoshuo "true" }}
+                {{ if ne .Params.disableduoshuo "true" }}
                     {{ partial "duoshuo.html" . }}
                 {{ end }}
             {{ end }}

layouts/section/about.html

@@ -7,13 +7,13 @@
     {{ .Content }}
 
     {{ if .Site.Params.enableDisqus }}
-        {{ if eq .Params.disabledisqus "true" }}
+        {{ if ne .Params.disabledisqus "true" }}
             {{ partial "disqus.html" . }}
         {{ end }}
     {{ end }}
 
     {{ if .Site.Params.enableDuoshuo }}
-        {{ if eq .Params.disableduoshuo "true" }}
+        {{ if ne .Params.disableduoshuo "true" }}
             {{ partial "duoshuo.html" . }}
         {{ end }}
     {{ end }}