Problem with PDF and TXT extensions

[ganiserb]

Hello, I've noticed that .txt and .pdf ending strings do not show any icon in the sample page (not even the default icon): https://exuanbo.xyz/file-icons-js/

At first I thought it was a problem with my project, but then I realized it's the only icon that has a different class name than the others:

https://github.com/exuanbo/file-icons-js/blob/master/lib/icons/.icondb.js#L1391

https://github.com/exuanbo/file-icons-js/blob/master/lib/icons/.icondb.js#L1690-L1702

If I have some time I will make a PR to fix it using Font Awesome icons.

[ganiserb]

Update, because it's getting buried. A solution can be found in this other pull request #204