8025741: Fix jdk/make/docs/Makefile to point to correct docs URL for JDK 8.

Reviewed-by: tbell

make/docs/Makefile

@@ -50,6 +50,7 @@ BUG_SUBMIT_LINE = <a href="$(BUG_SUBMIT_URL)">Submit a bug or feature</a>
 DEV_DOCS_URL-5 = http://java.sun.com/j2se/1.5.0/docs/index.html
 DEV_DOCS_URL-6 = http://download.oracle.com/javase/6/docs/index.html
 DEV_DOCS_URL-7 = http://download.oracle.com/javase/7/docs/index.html
+DEV_DOCS_URL-8 = http://download.oracle.com/javase/8/docs/index.html
 DEV_DOCS_URL = $(DEV_DOCS_URL-$(JDK_MINOR_VERSION))
 DOCS_BASE_URL = http://download.oracle.com/javase/7/docs