CH07: tone down beyond-bitcoin applications

Bitcoin can do things beyond money, but (as other text in the chapter
notes) this can be controversial.  Let's not oversell those other uses
here only to throw shade on them later.

chapters/authorization-authentication.adoc

@@ -706,10 +706,10 @@ spent.
 (nonpayment data)")))((("nonpayment data")))((("blockchain (the)",
 "nonpayment data recording")))((("digital notary services")))Bitcoin's
 distributed and timestamped ledger, the blockchain, has potential uses
-far beyond payments. Many developers have tried to use the transaction
+beyond payments. Many developers have tried to use the transaction
 scripting language to take advantage of the security and resilience of
-the system for applications such as digital notary services, stock
-certificates, and smart contracts. Early attempts to use bitcoin's
+the system for applications such as digital notary services
+and smart contracts. Early attempts to use bitcoin's
 script language for these purposes involved creating transaction outputs
 that recorded data on the blockchain; for example, to record a digital
 fingerprint of a file in such a way that anyone could establish