[clangd] Fix category in clangd-vscode's package.json

Summary:
When opening package.json, vscode shows:

  Use 'Programming  Languages' instead

Replacing "Languages" with this fixes it.

Reviewers: ilya-biryukov

Subscribers: arphaman, ilya-biryukov, ioeric, MaskRay, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D49253

llvm-svn: 337697