[Docs] Adjust Java API documentation to be in sync with latest changes

[ci skip]

docs/_config.yml

@@ -5,7 +5,7 @@
 #     {{ site.CONFIG_KEY }}
 #------------------------------------------------------------------------------
 
-FLINK_VERSION_STABLE: 0.6-SNAPSHOT # this variable can point to a SNAPSHOT version in the git source.
+FLINK_VERSION_STABLE: 0.6-incubating-SNAPSHOT # this variable can point to a SNAPSHOT version in the git source.
 FLINK_VERSION_SHORT: 0.6
 FLINK_ISSUES_URL: https://issues.apache.org/jira/browse/FLINK
 FLINK_GITHUB_URL:  https://github.com/apache/incubator-flink
@@ -32,4 +32,4 @@ redcarpet:
   # https://help.github.com/articles/github-flavored-markdown
   extensions: ["no_intra_emphasis", "fenced_code_blocks", "autolink",
                "tables", "with_toc_data", "strikethrough", "superscript",
-               "lax_spacing"]
\ No newline at end of file
+               "lax_spacing"]