Adds BackOfficeLogo to the ContentSettings (#6836)

Author: leekelleher

15/umbraco-cms/reference/configuration/contentsettings.md

@@ -26,6 +26,7 @@ The following snippet will give an overview of the keys and values in the conten
       "DisallowedUploadFiles": ["ashx", "aspx", "ascx", "config", "cshtml", "vbhtml", "asmx", "air", "axd", "xamlx"],
       "DisallowedUploadedFileExtensions": ["ashx", "aspx", "ascx", "config", "cshtml", "vbhtml", "asmx", "air", "axd", "xamlx"],
       "Error404Collection": [],
+      "BackOfficeLogo": "../media/qyci4xti/logo.png",
       "HideBackOfficeLogo": false,
       "Imaging": {
         "ImageFileTypes": ["jpeg", "jpg", "gif", "bmp", "png", "tiff", "tif"],
@@ -128,6 +129,10 @@ If you have multiple sites, with different cultures, setup in your tree then you
 
 If you have more than two sites and forget to add a 404 page and a culture, the default page will act as fallback. Same happens if you for some reason forget to define a hostname on a site.
 
+### Backoffice logo
+
+This setting can be used to set a custom image path to replace the Umbraco logo in backoffice.
+
 ### Hide backoffice logo
 
 This setting can be used to hide the Umbraco logo in backoffice.