Update name of the function (#1419)

Author: pusewicz

doc/vim-lsp.txt

@@ -2127,7 +2127,7 @@ To use semantic highlighting, you need Neovim highlights, or Vim with the
 To enable semantic highlighting, |g:lsp_semantic_enabled| should be set to `1`
 (it is `0` by default). You can check if semantic highlighting is enabled
 by running: >
-    echo lsp#ui#vim#semantic#is_enabled()
+    echo lsp#internal#semantic#is_enabled()
 
 vim-lsp provides |highlight| groups for each of the token types supported by
 the current LSP server. This includes highlight groups for each of the