add link to doc

Author: remicollet

README.md

@@ -13,7 +13,7 @@ It also provides additional functions from libxcrypt missing in core PHP:
 * `crypt_gensalt`: encode settings for passphrase hashing
 * `crypt_checksalt`: validate a crypt setting string
 
-See the Linux man pages.
+See the Linux man pages or [PHP Documentation](https://www.php.net/xpass)
 
 **Computation time**
 

package.xml

@@ -15,6 +15,8 @@ It also provides additional functions from libxcrypt missing in core PHP:
 * crypt_preferred_method
 * crypt_gensalt
 * crypt_checksalt
+
+See PHP documentation on https://www.php.net/xpass
 </description>
   <lead>
     <name>Remi Collet</name>