Theme fixes

Made srcref flexible
Changed background for inline code samples

Author: rozza

docs/reference/themes/mongodb/layouts/shortcodes/srcref.html

@@ -1 +1 @@
-https://github.com/mongodb/{{ .Page.Site.Data.mongodb.githubRepo }}/blob/{{ .Page.Site.Data.mongodb.githubBranch }}/{{ .Get 0 }}
+https://github.com/mongodb/{{ .Page.Site.Data.mongodb.githubRepo }}/blob/{{ .Page.Site.Data.mongodb.githubBranch }}/{{ if eq (in (.Get 0) "src/") false }}src/{{ end }}{{ .Get 0 }}

docs/reference/themes/mongodb/static/css/overrides.css

@@ -77,6 +77,10 @@
 }
 
 code {
-  background-color: #ddd;
+  background-color: #f5f6f7;
   color: #494747;
 }
+
+a code {
+  color: #006cbc;
+}