Added section on how to do customization with coc.nvim.

coc.nvim.md

@@ -101,3 +101,54 @@ nn <silent><buffer> <C-k> :call CocLocations('ccls','$ccls/navigate',{'direction
 nn <silent><buffer> <C-j> :call CocLocations('ccls','$ccls/navigate',{'direction':'R'})<cr>
 nn <silent><buffer> <C-h> :call CocLocations('ccls','$ccls/navigate',{'direction':'U'})<cr>
 ```
+
+### Customization with coc.nvim
+
+Options listed in [Customization](https://github.com/MaskRay/ccls/wiki/Customization) can be passed to CCLS via `initializationOptions` in the Coc configuration file. For example, if to direct ccls to look for `compile_commands.json` in the project `build` directory, you could add an entry for `compilationDatabaseDirectory`, and update `rootPatterns` accordingly.
+
+```json
+{
+  "languageserver": {
+    "ccls": {
+      "command": "ccls",
+      "filetypes": ["c", "cpp", "cuda", "objc", "objcpp"],
+      "rootPatterns": [".ccls-root", "build/compile_commands.json"],
+      "initializationOptions": {
+        "cache": {
+          "directory": ".ccls-cache"
+        },
+        "client": {
+          "snippetSupport": true
+        },
+        "compilationDatabaseDirectory": "build"
+      }
+    }
+  }
+}
+```
+
+Options like `clang.extraArgs` may be similarly be added using the same syntax as `client.snippetSupport` in the example above. For example, we can support C++20 by default by passing `-std=c++20` as an extra argument to clang: 
+
+```json
+{
+  "languageserver": {
+    "ccls": {
+      "command": "ccls",
+      "filetypes": ["c", "cpp", "cuda", "objc", "objcpp"],
+      "rootPatterns": [".ccls-root", "build/compile_commands.json"],
+      "initializationOptions": {
+        "cache": {
+          "directory": ".ccls-cache"
+        },
+        "client": {
+          "snippetSupport": true
+        },
+        "compilationDatabaseDirectory": "build",
+        "clang": { 
+          "extraArgs": [ "-std=c++20" ] 
+        }
+      }
+    }
+  }
+}
+```