🐛 FIX: correct broken readme links with prefixing

Signed-off-by: Jonas Sulzer <jonas@violoncello.ch>

README.md

@@ -46,10 +46,10 @@ To enable SSL connections via `ftps`, append a second parameter `true`:
 ### Dependencies
 PHP automatically contains basic FTP support.
 
-For SSL-secured FTP connections via ftps, the PHP [openssl extension][0]
+For SSL-secured FTP connections via ftps, the PHP [openssl extension][FTP_0]
 needs to be activated.
 
-[0]: http://php.net/openssl
+[FTP_0]: http://php.net/openssl
 
 
 
@@ -77,16 +77,16 @@ only users from this domain will be allowed to login. After successfull
 login the domain part will be striped and the rest used as username in
 NextCloud. e.g. 'username@example.com' will be 'username' in NextCloud.
 
-Read the [imap_open][0] PHP manual page to learn more about the allowed
+Read the [imap_open][IMAP_0] PHP manual page to learn more about the allowed
 parameters.
 
-[0]: http://php.net/imap_open#refsect1-function.imap-open-parameters
+[IMAP_0]: http://php.net/imap_open#refsect1-function.imap-open-parameters
 
 
 ### Dependencies
-The PHP [IMAP extension][1] has to be activated.
+The PHP [IMAP extension][IMAP_1] has to be activated.
 
-[1]: http://php.net/imap
+[IMAP_1]: http://php.net/imap
 
 
 
@@ -136,7 +136,7 @@ Add the following to your `config.php`:
 BasicAuth
 ------
 
-Authenticate users by an [HTTP Basic access authentication][1]  call. 
+Authenticate users by an [HTTP Basic access authentication][BasicAuth_0]  call.
 HTTP server of your choice to authenticate. It should return HTTP 2xx for correct credentials and an appropriate other error code for wrong ones or refused access.
 
 ### Configuration
@@ -152,7 +152,7 @@ Add the following to your `config.php`:
     ),
 
 
-[1]: https://en.wikipedia.org/wiki/Basic_access_authentication
+[BasicAuth_0]: https://en.wikipedia.org/wiki/Basic_access_authentication
 
 Alternatives
 ------------