Add documentation on updating SELinux permissions of files in public_html

[JSpewock]

If you create a file in your home directory it is given the SELinux security type user_home_t and move it into your public_html directory, this type does not change and forbids you from accessing the file via HTML. You need to change the type of file using chcon to httpd_user_content_t in order for it to be accessed.