Can't use this extensions on Github Readme files containing titles

[iaeiou]

Hi there,

when I try to get the Markdown from a Github Reame file, the titles seem to break the output.

How to reproduce?

• Visit any Readme on Github, for example the documentation of Micro
• Select some text including titles and subtitles
• Right-click → Copy selection as Markdown
• Paste in any text editor

Wich problem occurs?

The pasted output is broken: everything works fine until the first subtitle. Then the first part of the selection is repeated

Thanks for your amazing extension, keep on the great work!