[clangd] Bump recommended gRPC version (1.33.2 -> 1.36.3)

[kbobyrev]

Summary

Context: https://github.com/clangd/clangd/pull/783

[kbobyrev]

I don't really know if we should do this before the buildbot update so I just wanted to know your opinion @kadircet.

[kadircet]

I think we should wait for build bot update on this one too. Otherwise we might miss some breakages.

[kbobyrev]

Makes sense, thanks! Putting this on hold.

[kadircet]

looks like the https://lab.llvm.org/buildbot/#/builders/131 is green after the version bump. thanks for taking care of this!

clang-tools-extra/clangd/index/remote/README.md

 Another way of installing gRPC and Protobuf is building from sources using
 CMake (we need CMake config files to find necessary libraries in LLVM). The
 easiest way of doing that would be to choose a directory where you want to
 install so that the installation files are not copied to system root and you
 can easily uninstall gRPC or use different versions.
 
 ```bash
 # Get source code.
-$ git clone -b v1.33.2 https://github.com/grpc/grpc
+$ git clone -b v1.36.3 https://github.com/grpc/grpc
 $ cd grpc
 $ git submodule update --init
 # Choose directory where you want gRPC installation to live.
 $ export GRPC_INSTALL_PATH=/where/you/want/grpc/to/be/installed
 # Build and install gRPC to ${GRPC_INSTALL_PATH}
 $ mkdir build; cd build
 $ cmake -DgRPC_INSTALL=ON -DCMAKE_INSTALL_PREFIX=${GRPC_INSTALL_PATH} -DCMAKE_BUILD_TYPE=Release ..
 $ make install