You are able to see this document because of two things

the .htaccess file in this directory

AuthUserFile /usr/local/lib/htpasswd/passwd_ex1

AuthGroupFile /dev/null

AuthName ExampleByPassword

AuthType Basic





<Limit GET>

require user html

</Limit>

  

and the password file (kept elsewhere)

This was generated by using

      htpasswd -c /usr/local/lib/htpasswd/passwd_ex1 html