Docs: Fix CLI syntax for --bullets

Author: paulmelnikow

README.md

@@ -49,7 +49,7 @@ Usage: markdown-toc [options] <input>
   --append:     Append a string to the end of the TOC
 
   --bullets:    Bullets to use for items in the generated TOC
-                (Supports multiple bullets: --bullets "*" --bullets "-" --bullets "+")
+                (Supports multiple bullets: --bullets="*" --bullets="-" --bullets="+")
                 (Default is "*".)
 
   --maxdepth:   Use headings whose depth is at most maxdepth
@@ -356,4 +356,4 @@ Released under the [MIT License](LICENSE).
 
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-_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on September 19, 2017._
+_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on September 19, 2017._