docs: add mstojanovic as a contributor (#104)

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>
Co-authored-by: Dorian Karter <dkarter@users.noreply.github.com>

Author: allcontributors[bot]

.all-contributorsrc

@@ -129,6 +129,15 @@
         "code",
         "bug"
       ]
+    },
+    {
+      "login": "mstojanovic",
+      "name": "Marko Stojanovic",
+      "avatar_url": "https://avatars.githubusercontent.com/u/3449343?v=4",
+      "profile": "https://github.com/mstojanovic",
+      "contributions": [
+        "doc"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -3,7 +3,7 @@
 [![Build Status](https://travis-ci.org/dkarter/bullets.vim.svg?branch=master)](https://travis-ci.org/dkarter/bullets.vim) 
 
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-12-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-13-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 # Description
@@ -353,6 +353,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <td align="center"><a href="https://github.com/harshad1"><img src="https://avatars0.githubusercontent.com/u/1940940?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harshad Srinivasan</b></sub></a><br /><a href="https://github.com/dkarter/bullets.vim/commits?author=harshad1" title="Code">💻</a> <a href="https://github.com/dkarter/bullets.vim/issues?q=author%3Aharshad1" title="Bug reports">🐛</a></td>
     <td align="center"><a href="https://erickchacon.github.io/"><img src="https://avatars2.githubusercontent.com/u/7862458?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Erick A. Chacón Montalván</b></sub></a><br /><a href="#ideas-ErickChacon" title="Ideas, Planning, & Feedback">🤔</a></td>
     <td align="center"><a href="https://samgriesemer.com"><img src="https://avatars.githubusercontent.com/u/19940657?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sam Griesemer</b></sub></a><br /><a href="https://github.com/dkarter/bullets.vim/commits?author=samgriesemer" title="Code">💻</a> <a href="https://github.com/dkarter/bullets.vim/issues?q=author%3Asamgriesemer" title="Bug reports">🐛</a></td>
+    <td align="center"><a href="https://github.com/mstojanovic"><img src="https://avatars.githubusercontent.com/u/3449343?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Marko Stojanovic</b></sub></a><br /><a href="https://github.com/dkarter/bullets.vim/commits?author=mstojanovic" title="Documentation">📖</a></td>
   </tr>
 </table>