Fix error docs to change icon

[FrederickChan]

I've been modifying my work and I realized that you had a incorrect doc after looking into fileinput.js

The problem:

https://plugins.krajee.com/file-input/plugin-options#layoutTemplates

   icon: '<span class="bi-file-earmark-fill kv-caption-icon"></span>',
    caption: '<input readonly class="file-caption-name form-control {class}">\n',
    btnDefault: '<button type="{type}" title="{title}" class="{css}"{status} {tabIndexConfig}>{icon}{label}</button>',

This part is not "icon" but "fileIcon".

According to your latest release on github, this should be changed to:

     layoutTemplates: {                         
                            fileIcon:  '<i class="fas fa-fish"></i>',     

[kartik-v]

Fixed in docs.