Add sharing to purchase dialog

app/src/main/java/org/tasks/billing/PurchaseDialog.kt

@@ -139,6 +139,7 @@ _${getString(R.string.account_not_included)}_
 ---                
 #### ${getString(R.string.tasks_org_account)}
 * ${getString(R.string.tasks_org_description)}
+* [${getString(R.string.tasks_org_share)}](${getString(R.string.url_sharing)})
 * [${getString(R.string.upgrade_third_party_apps)}](${getString(R.string.url_app_passwords)})
 * ${getString(R.string.upgrade_google_places)}
 * [${getString(R.string.upgrade_coming_soon)}](${getString(R.string.help_url_sync)})

app/src/main/res/values/keys.xml

@@ -32,6 +32,7 @@
   <string name="url_freenode">https://webchat.freenode.net/?channels=tasks</string>
   <string name="url_sponsor">https://github.com/sponsors/abaker</string>
   <string name="url_app_passwords">https://tasks.org/passwords</string>
+  <string name="url_sharing">https://tasks.org/sharing</string>
 
   <!-- Eventually these should be moved to strings.xml for translation -->
   <string name="upgrade_sync_self_hosted">Sync with third-party apps and services</string>

app/src/main/res/values/strings.xml

@@ -533,6 +533,7 @@ File %1$s contained %2$s.\n\n
   <string name="create_new_tag">Create \"%s\"</string>
   <string name="choose_synchronization_service">Select a platform</string>
   <string name="tasks_org_description">Synchronize your tasks with Tasks.org</string>
+  <string name="tasks_org_share">Share lists with other users</string>
   <string name="google_tasks_selection_description">Basic service that synchronizes with your Google account</string>
   <string name="caldav_selection_description">Synchronization based on open internet standards</string>
   <string name="etesync_selection_description">Open source, end-to-end encrypted synchronization</string>