fixed width of sample image

Author: manfred-kaiser

doc/quickstart.rst

@@ -18,7 +18,7 @@ In cases, when no agent was forwarded, SSH-MITM can rediredt the session to a ho
 
     <p align="center">
     <a href="https://www.ssh-mitm.at/img/ssh-mitm-password.png">
-        <img alt="SSH-MITM intercepting password login" title="SSH-MITM" src="https://www.ssh-mitm.at/img/ssh-mitm-password.png" width="650" >
+        <img alt="SSH-MITM intercepting password login" title="SSH-MITM" src="https://www.ssh-mitm.at/img/ssh-mitm-password.png" width="75%" >
     </a>
     <p align="center">ssh man-in-the-middle (ssh-mitm) server for security audits supporting<br> <b>publickey authentication</b>, <b>session hijacking</b> and <b>file manipulation</b></p>
     <p align="center">