add .clangd to gitignore

I use .clangd to configure compiler flags for the lsp (language server)
I use in nvim.

Changelog-None

Signed-off-by: Peter Neuroth <pet.v.ne@gmail.com>

Author: nepet

.gitignore

@@ -85,6 +85,7 @@ plugins/cln-grpc
 plugins/clnrest
 plugins/wss-proxy
 plugins/cln-bip353
+.clangd
 
 # Build directories
 bionic/