Add the option to use a logo for the top left site title

README.md

 If you add a key of `show_reading_time` true to either the Config Params, a page or section's front matter, articles will show the reading time and word count.
 
 
+### Logo
+
+You can replace the title of your site in the top left corner of each page with your own logo. To do that put your own logo into the `static` directory of your website, and add the `logo` parameter to the site params in your config file. For example:
+
+```
+[params]
+  logo = "img/logo.svg"
+```
+
+
 ### Nearly finished
 
 In order to see your site in action, run Hugo's built-in local server.

layouts/partials/site-navigation.html

 <nav class="pv3 ph3 ph4-ns" role="navigation">
   <div class="flex-l justify-between items-center center">
     <a href="{{ .Site.BaseURL }}" class="f3 fw2 hover-white no-underline white-90 dib">
+    {{ if .Site.Params.Logo }}
+      <img src="{{ .Site.Params.Logo | relURL }}" alt="{{ .Site.Title }}" />
+    {{ else }}
       {{ .Site.Title }}
+    {{ end }}
     </a>
     <div class="flex-l items-center">
       {{ partial "i18nlist.html" . }}