Add sponsors.dd to PAGES_ROOT

Author: wilzbach

posix.mak

@@ -359,7 +359,7 @@ PAGES_ROOT=$(SPEC_ROOT) 404 acknowledgements areas-of-d-usage \
 	gsoc2011 gsoc2012 gsoc2012-template hijack howto-promote htod index install \
 	intro-to-datetime lazy-evaluation menu migrate-to-shared mixin \
 	orgs-using-d overview pretod rationale rdmd regular-expression resources safed \
-	search template-comparison templates-revisited tuple \
+	search sponsors template-comparison templates-revisited tuple \
 	variadic-function-templates warnings wc windbg
 
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