Added H1 markdown highlight

Kushagra · web-flow · commit 5b1fa1bdd297 · 2018-08-27T18:15:47.000+05:30
Added HackerOne syntax for highlighting text in markdown. To preview the "This text is highlighted" I have used a screenshot because GitHub doesn't seem to support &lt;mark&gt; or &lt;span&gt; with color's.
diff --git a/docs/hackers/using-markdown.md b/docs/hackers/using-markdown.md
@@ -40,6 +40,7 @@ _This text is underlined_
 **This text is bold**
 __This text is bold__
 --This text is deleted--
+==This text is highlighted==
 ```
 *This text is italicized*
 
@@ -51,6 +52,8 @@ __This text is bold__
 
 ~~This text is deleted~~
 
+![markdown-0](./images/markdown-0.png)
+
 ### LISTS
 #### Unordered Lists
 ```
