Bazel: Bump java docs api to 11

This is fixing build api breakage with newer Java versions:

javadoc: error - The code being documented uses modules but the \
packages defined in https://docs.oracle.com/javase/8/docs/api/
are in the unnamed module.

The problem was reported in: [1].

Test Plan:

Confirm that `bazel build :api` works as expected with Bazel@HEAD.

[1] https://github.com/bazelbuild/bazel/issues/10802

Change-Id: If6187865c440251c7aca03c27f7afe118d97a155
diff --git a/tools/bzl/javadoc.bzl b/tools/bzl/javadoc.bzl
index 029e5ca..eecafb44 100644
--- a/tools/bzl/javadoc.bzl
+++ b/tools/bzl/javadoc.bzl
@@ -26,7 +26,7 @@
     transitive_jar_paths = [j.path for j in transitive_jars.to_list()]
     dir = ctx.outputs.zip.path + ".dir"
     source = ctx.outputs.zip.path + ".source"
-    external_docs = ["https://docs.oracle.com/javase/8/docs/api"] + ctx.attr.external_docs
+    external_docs = ["https://docs.oracle.com/en/java/javase/11/docs/api"] + ctx.attr.external_docs
     cmd = [
         "TZ=UTC",
         "export TZ",