The file still exists in docs/analyzer/, but it won't be linked to from
clang.llvm.org or processed as part of the default Sphinx doc-build.
RegionStore has changed a lot from what Ted and Zhongxing describe here!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@170260 91177308-0d34-0410-b5e6-96231b3b80d8