Update documentation of the create-account command

The documentation states that the command is used for creating
user accounts for batch/role access.  However this is not always
the case; it is possible to create an account for a real person
with an email address and name.

Update the documentation to say that if the account is created
without an email address, it may only be used for batch/role
access.

Change-Id: I213708e32f98585632810023afd9eca3e6f3df8e

Documentation/cmd-create-account.txt

diff --git a/Documentation/cmd-create-account.txt b/Documentation/cmd-create-account.txt
index 16b2eb5..85b9b56 100644
--- a/Documentation/cmd-create-account.txt
+++ b/Documentation/cmd-create-account.txt
@@ -18,9 +18,11 @@
 
 DESCRIPTION
 -----------
-Creates a new internal only user account for batch/role access, such
-as from an automated build system or event monitoring over
-link:cmd-stream-events.html[gerrit stream-events].
+Creates a new internal-only user account.
+
+If the account is created without an email address, it may only be
+used for batch/role access, such as from an automated build system
+or event monitoring over link:cmd-stream-events.html[gerrit stream-events].
 
 If LDAP authentication is being used, the user account is created
 without checking the LDAP directory.  Consequently users can be