Update legend

doc/rfc/INDEX

 This is an index of RFC contained in this directory:
 
-STD	Standard
-DS	Draft Standard
-PS	Proposed Standard
-
-I	Information
-E	Experimental
-
 rfc1274.txt COSINE and Internet X.500 Schema (PS)
 rfc1275.txt X.500 Replication Requirements (I)
 rfc1279.txt X.500 and Domains (E)
@@ -55,4 +48,13 @@ rfc2830.txt LDAPv3: StartTLS (PS)
 rfc2831.txt SASL/DIGEST-MD5 (PS)
 rfc2849.txt LDIFv1 (PS)
 
+Legend:
+STD	Standard
+DS	Draft Standard
+PS	Proposed Standard
+I	Information
+E	Experimental
+FYI	For Your Information 
+BCP	Best Common Practice
+
 $OpenLDAP$