Document touch command's TTR reset

This fixes #188.

doc/protocol.md

@@ -253,7 +253,8 @@ There are two possible responses:
 
 #### `touch` command
 
-The `touch` command allows a worker to request more time to work on a job. This is useful for jobs that potentially take a long time, but you still want the benefits of a TTR pulling a job away from an unresponsive worker.  A worker may periodically tell the server that it's still alive and processing a job (e.g. it may do this on `DEADLINE_SOON`).
+The `touch` command allows a worker to request more time to work on a job. This is useful for jobs that potentially take a long time, but you still want the benefits of a TTR pulling a job away from an unresponsive worker.  A worker may periodically tell the server that it's still alive and processing a job (e.g. it may do this on `DEADLINE_SOON`). The command postpones the auto release of a reserved job until TTR seconds from when the command is issued.
+
 
 The touch command looks like this:
 

doc/protocol.txt

@@ -309,7 +309,8 @@ The "touch" command allows a worker to request more time to work on a job.
 This is useful for jobs that potentially take a long time, but you still want
 the benefits of a TTR pulling a job away from an unresponsive worker.  A worker
 may periodically tell the server that it's still alive and processing a job
-(e.g. it may do this on DEADLINE_SOON).
+(e.g. it may do this on DEADLINE_SOON). The command postpones the auto
+release of a reserved job until TTR seconds from when the command is issued.
 
 The touch command looks like this: