The problem isn't the permissions, but the file's SELinux context. You probably moved Documentation.html into the /var/www/html directory, maintaining its (incorrect) context. When you copied the file, the newly created file inherited the (correct) directory context.
You can see this with 'ls -Z' on the files in question. What you probably need to do is:
chcon -t httpd_sys_content_t /var/www/html/Documentation.html
Documentation on SELinux is here
, assuming you are using the current FC5.