GUACAMOLE-773: Bring license details of bundled Java dependencies up-to-date.

doc/licenses/guava-30.1.1-jre/README

@@ -0,0 +1,8 @@
+Guava: Google Core Libraries for Java (https://github.com/google/guava)
+-----------------------------------------------------------------------
+
+    Version: 30.1.1-jre
+    From: 'Google Inc.' (http://www.google.com/)
+    License(s):
+        Apache v2.0
+

doc/licenses/guava-30.1.1-jre/maven-coordinates.txt

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+com.google.guava:failureaccess:jar:1.0.1
+com.google.guava:guava:jar:30.1.1-jre
+com.google.guava:listenablefuture:jar:9999.0-empty-to-avoid-conflict-with-guava