Added addthis.com draft to trackers. Progress towards #136.

trackers/addthis.com/index.md

+# addthis.com
+
+> Brief description of the tracker – [Source](link)
+
+## Ethical design violations
+
+  * Tracker
+
+<!-- Other ethical design violation badges go here. Valid ones are:
+  * Aggressive
+  * Doorslam
+  * Clickbait
+  * Fingerprint
+  * Web bug
+-->
+
+## Block rule
+
+<!--
+	The original block rule is automatically generated by Better Inspector.
+	If you want to edit it, you may. The Inspector will not touch your edits
+	in future passes.
+-->
+
+**Block domain** addthis.com
+
+```mson
+- trigger:
+	- url-filter: addthis.com
+	- load-type: third-party
+- action:
+	- type: block
+```
+
+## Popularity
+
+  * <!-- foundOnNumberOfSites -->(foundOnNumberOfSites)<!-- /foundOnNumberOfSites -->
+
+<!-- Optional:
+## Notes
+  * Any special notes you have may go here.
+-->
+
+## Notes
+
+  * None yet.
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