docs: Add 10.4 sha256 sums, news item and link release notes

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
(cherry picked from commit af0c82099b955f10471c15cb7a4dc8db29b84963)

Conflicts:
	docs/index.html
	docs/relnotes.html
diff --git a/docs/relnotes.html b/docs/relnotes.html
index 5691a94..267ffc2 100644
--- a/docs/relnotes.html
+++ b/docs/relnotes.html
@@ -21,6 +21,7 @@
 </p>
 
 <ul>
+<li><a href="relnotes/10.4.html">10.4 release notes</a>
 <li><a href="relnotes/10.3.5.html">10.3.5 release notes</a>
 <li><a href="relnotes/10.3.4.html">10.3.4 release notes</a>
 <li><a href="relnotes/10.3.3.html">10.3.3 release notes</a>