docs: add guide for regaddr

README.md

@@ -130,15 +130,23 @@ Print all info about the public key
 
     ./keyinfo -v privatekey.dat
 
-### regaddr_3ld
+### regaddr
+
+Generate authentication string to register a domain on stats.i2p
+
+    ./regaddr domain.dat domain.i2p > auth_string.txt
+    cat auth_string.txt
 
-Generate authentication string for stats.i2p in 3 steps
+Send output of auth_string to http://stats.i2p/i2p/addkey.html
+To register a subdomain, use [`regaddr_3ld`](#regaddr_3ld)
+
+### regaddr_3ld
 
-#### 
+Generate authentication string to register a subdomain on stats.i2p in 3 steps
 
     ./regaddr_3ld step1 sub_domain.dat sub.domain.i2p > step1.txt
     ./regaddr_3ld step2 step1.txt domain.dat domain.i2p > step2.txt
     ./regaddr_3ld step3 step2.txt sub_domain.dat > step3.txt
     cat step3.txt
 
-Send output from step3 to http://stats.i2p/i2p/addkey.html to register subdomain on stats.i2p
+Send output from step3 to http://stats.i2p/i2p/addkey.html