Minor clarifications on .ccls file contents

Project-Setup.md

@@ -200,10 +200,12 @@ with open(os.path.join(sys.argv[1], 'compile_commands.json')) as f:
 `.ccls` is a line-based text file at the project root. Its specifies compiler
 flags needed to properly index your code: `-I` `-D` etc.  The first line
 specifies the compiler driver (usually `clang`), while each subsequent lines
-specifies one argument to be added to the compiler command line.
+specifies **one** argument to be added to the compiler command line. Blank and "# comment"
+lines are ignored.
 
 No whitespace splitting is performed on the argument, thus `-I foo` cannot be
-used (use `-Ifoo` or `-I\nfoo` for example).
+used (use `-Ifoo` or `-I\nfoo` for example). If an include path has spaces enter that
+as without escaping the spaces. For example, `-I/include/path/with a space/to/dir/foo`.
 
 Subdirectories of the project can also contain `.ccls` files, if needed, to
 specify compiler flags specific to those directories.