week19.txt: add tasks about broken IRIs

timeline/week19.txt

@@ -31,5 +31,12 @@ Week 19 (04.05.-10.05.)
 	[ ]  look at other graph databases; we need to at
 	     least look at alternatives, right?
 
+[ ] broken IRIs
+
+	[ ] write down what's wrong exactly; it's not very helpful to
+	    just report that "something is wrong, is it?
+
+	[ ] report to authors of exporters
+
 References
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