[FAB-13018] Commit instead of commitment

For glossary. Per issue, Commitment is something
in cryptography when you send a hidden promise
for a value, i.e - a coin toss, and that you
cannot change your promise later on when you
reveal the value

Change-Id: If04d61a88d2c77a7d82565497ae139f170aaf9fe
Signed-off-by: joe-alewine <Joe.Alewine@ibm.com>

docs/source/glossary.rst

@@ -134,10 +134,10 @@ a channel in order to interact with it.  Channels are defined by a
 Configuration-Block_.
 
 
-.. _Commitment:
+.. _Commit:
 
-Commitment
-----------
+Commit
+------
 
 Each Peer_ on a channel validates ordered blocks of
 transactions and then commits (writes/appends) the blocks to its replica of the