[clangd] NFC: Cleanup clangd help message

[kbobyrev]

Summary

Add missed space, fix a typo.

[ioeric]

lg

clang-tools-extra/clangd/tool/ClangdMain.cpp

static llvm::cl::opt<Path> InputMirrorFile(
     "input-mirror-file",
     llvm::cl::desc(
         "Mirror all LSP input to the specified file. Useful for debugging."),
     llvm::cl::init(""), llvm::cl::Hidden);
 
 static llvm::cl::opt<bool> EnableIndex(
     "index",
     llvm::cl::desc("Enable index-based features such as global code completion "
-                   "and searching for symbols."
+                   "and searching for symbols. "
                    "Clang uses an index built from symbols in opened files"),
     llvm::cl::init(true));
 
 static llvm::cl::opt<bool>
     ShowOrigins("debug-origin",
                 llvm::cl::desc("Show origins of completion items"),
                 llvm::cl::init(clangd::CodeCompleteOptions().ShowOrigins),
                 llvm::cl::Hidden);
 
 static llvm::cl::opt<bool> HeaderInsertionDecorators(
     "header-insertion-decorators",
     llvm::cl::desc("Prepend a circular dot or space before the completion "
-                   "label, depending on wether "
+                   "label, depending on whether "
                    "an include line will be inserted or not."),
     llvm::cl::init(true));
 
 static llvm::cl::opt<Path> YamlSymbolFile(
     "yaml-symbol-file",
     llvm::cl::desc(
         "YAML-format global symbol file to build the static index. Clangd will "
         "use the static index for global code completion.\n"