Edited ch04_keys.adoc with Atlas code editor

ch04_keys.adoc

@@ -1608,7 +1608,7 @@ such as vanity addresses and paper wallets.
 
 ==== Vanity Addresses
 
-Vanity addresses are valid Bitcoin
+Vanity((("public key cryptography", "vanity addresses", id="pub-key-vanity")))((("vanity addresses", id="vanity-addr"))) addresses are valid Bitcoin
 addresses that contain human-readable messages. For example,
 +1LoveBPzzD72PUXLzCkYAtGFYmK5vYNR33+ is a valid address that contains
 the letters forming the word "Love" as the first four base58 letters.
@@ -1810,7 +1810,7 @@ gives discount pricing to Eugenia.
 // https://github.com/MakisChristou/vanitybech
 
 We don't expect to see many vanity addresses in
-the future unless the preceding problems are solved.
+the future unless the preceding problems ((("public key cryptography", "vanity addresses", startref="pub-key-vanity")))((("vanity addresses", startref="vanity-addr")))are solved.
 
 [[paper_wallets]]
 ==== Paper Wallets