Add donate button config instructions (#11286)

* Add donate button config instructions
* add donate_button to example props
* add donate to example props

docs/deployment/customization/application.properties-Reference.md

@@ -50,6 +50,14 @@ skin.show_about_tab=
 
 **Note:** `skin.show_tools_tab` refers to the `Visualize Your Data` tab, while `skin.show_data_tab` refers to the `Data Sets` tab.
 
+### Show donate button
+
+We kindly ask for your support by enabling the “Donate” button on your portals to help fund our mission. The button will direct users to https://docs.cbioportal.org/donate/, where they can learn more about how the funding is utilized. You can activate it through:
+
+```
+skin.show_donate_button=true
+```
+
 ### Cross Cancer Study Query Default
 
 The cross cancer study query default is a list of studies used when querying one or more genes and not specifying a specific study or list of studies. There are two ways in which the default cross cancer study list is used:

src/main/resources/application.properties.EXAMPLE

@@ -69,6 +69,9 @@ skin.show_tutorials_tab=true
 skin.show_faqs_tab=true
 skin.show_tools_tab=true
 skin.show_about_tab=true
+# We kindly ask for your support by enabling the "Donate" button
+# https://cbioportal.org/donate
+# skin.show_donate_button=true
 
 # settings controlling the whats new blurb
 skin.right_nav.whats_new_blurb=<p> &bull;<a href="news.jsp"> <b>New data and features released</b></a><br/> &bull;<a href="tools.jsp"> <b>New tools released</b></a> </p> <form action="https://groups.google.com/group/cbioportal-news/boxsubscribe"> &nbsp;&nbsp;&nbsp;&nbsp;<b>Sign up for low-volume email news alerts:</b></br> &nbsp;&nbsp;&nbsp;&nbsp;<input type="text" name="email"> <input type="submit" name="sub" value="Subscribe"> </form> &nbsp;&nbsp;&nbsp;&nbsp;<b>Or follow us <a href="http://www.twitter.com/cbioportal"><i>@cbioportal</i></a> on Twitter</b>