Update .gitignore for clangd

MForster · MForster · commit a11028f27abc · 2020-07-17T07:01:31.000+02:00
The clangd cache is now stored in a .cache directory: https://reviews.llvm.org/D78501
diff --git a/.gitignore b/.gitignore
@@ -41,6 +41,7 @@ docs/_build
 .vs
 
 # clangd
+.cache
 .clangd
 
 #==============================================================================#
