docs: update documentation with command option and --cwd warning

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: greggh

doc/claude-code.txt

@@ -107,6 +107,8 @@ default configuration:
     git = {
       use_git_root = true,     -- Set CWD to git root when opening Claude Code (if in git project)
     },
+    -- Command settings
+    command = "claude",        -- Command used to launch Claude Code (do not include --cwd)
     -- Keymaps
     keymaps = {
       toggle = {