SAA: Update disambiguation

Reported 
https://forums.zotero.org/discussion/89711/issue-with-society-for-american-archaeology-format#latest 
and confirmed with guidelines. Disambiguation 3.4.7 clarifies that 
disambiguation is by-cite

society-for-american-archaeology.csl

@@ -341,7 +341,7 @@
   <macro name="original-date">
     <date date-parts="year" form="text" variable="original-date"/>
   </macro>
-  <citation et-al-min="3" et-al-use-first="1" disambiguate-add-year-suffix="true" disambiguate-add-names="true" disambiguate-add-givenname="false" collapse="year">
+  <citation et-al-min="3" et-al-use-first="1" disambiguate-add-year-suffix="true" disambiguate-add-names="true" disambiguate-add-givenname="true" collapse="year">
     <sort>
       <key macro="contributors"/>
       <key variable="issued"/>