Add cross references and semantic navigation

Visual-Studio-Code.md

@@ -48,3 +48,48 @@ The Visual Studio Code ccls extension supports [semantic highlighting](https://m
 "ccls.highlighting.enabled.staticMemberVariables": true,
 "ccls.highlighting.enabled.globalVariables": true,
 ```
+
+### Cross references
+
+You could set custom lookup using keybindings. Use command palette (`ctrl + shift + p` by default) -> `Open keyboard shortcuts file`
+
+```javascript
+// functions called by current selected function, up to 3rd level.
+{"key":"<ctrl-shift-alt-c>","command":"ccls.call","args":{"callee":true,"levels":3}}
+
+// functions that call this function. This is what "Show Cross References" shows by default
+{"key":"<your-shortcuts>","command":"ccls.call"}
+
+// see inheritance instead of base
+{"key":"<your-shortcuts>","command":"ccls.base","args":{"derived":true,"levels":2}}
+
+// nested classes / types in a namespace (kind: 2)
+{"key":"<your-shortcuts>","command":"ccls.member","args":{"kind":2}}
+
+// member functions / functions in a namespace(kind 3)
+{"key":"<your-shortcuts>","command":"ccls.member","args":{"kind":3}}
+```
+
+For VSCodeVim users, here's how to set arguments in User Settings (`settings.json`) 
+```json
+    "vim.normalModeKeyBindingsNonRecursive": [
+        {
+            "before":["<leader>","t"],
+            "commands":[{"command":"ccls.call","args":{"levels":2,"callee":true}}]
+        }
+    ]
+```
+So you could hit `<space>-t` to see callees up to 3rd level if you set `<leader>` to `<space>`
+
+### Semantic Navigation
+
+The command is `ccls.navigate`, which need an argument `direction`. ("D" => first child declaration "L" => previous declaration "R" => next declaration "U" => parent declaration)
+
+```json
+    "vim.normalModeKeyBindingsNonRecursive": [
+        {"before":["<leader>","j"],"commands":[{"command":"ccls.navigate","args":{"direction":"R"}}]},
+        {"before":["<leader>","k"],"commands":[{"command":"ccls.navigate","args":{"direction":"L"}}]},
+        {"before":["<leader>","h"],"commands":[{"command":"ccls.navigate","args":{"direction":"U"}}]},
+        {"before":["<leader>","l"],"commands":[{"command":"ccls.navigate","args":{"direction":"D"}}]}
+    ]
+```