Documentation: Use "link" icon from Silk Icons for anchor image

Other parts of the UI are using Silk Icons, and the link icon
from this set is nicer than the one currently used.

This removes dependency on the "Freebie: Application Icon Set"
license.

Change-Id: I1db8f2c1dc976001975b733ced1d04bdd9b86e07

gerrit-gwtui/BUCK

@@ -25,7 +25,6 @@ gwt_module(
   gwt_xml = 'src/main/java/%s.gwt.xml' % MODULE.replace('.', '/'),
   resources = glob(['src/main/java/**/*']),
   deps = [
-    ':freebie_application_icon_set',
     ':silk_icons',
     '//gerrit-gwtui-common:diffy_logo',
     '//gerrit-gwtui-common:client',
@@ -40,14 +39,6 @@ gwt_module(
   ],
 )
 
-java_library(
-  name = 'freebie_application_icon_set',
-  deps = [
-    '//lib:LICENSE-freebie_application_icon_set',
-    '//lib:LICENSE-CC-BY3.0',
-  ],
-)
-
 java_library(
   name = 'silk_icons',
   deps = [

lib/BUCK

@@ -10,7 +10,6 @@ define_license(name = 'CC-BY3.0')
 define_license(name = 'clippy')
 define_license(name = 'codemirror')
 define_license(name = 'diffy')
-define_license(name = 'freebie_application_icon_set')
 define_license(name = 'h2')
 define_license(name = 'jgit')
 define_license(name = 'jsch')

lib/LICENSE-freebie_application_icon_set

@@ -1 +0,0 @@
-link:http://creativecommons.org/licenses/by/3.0/us/[CC-BY 3.0] (c) Matt Gentile, link:http://tympanus.net/codrops/2012/10/02/freebie-application-icon-set-png-psd-csh/[Freebie: Application Icon Set]