Add documentation for a new way to reference Named Parameters

Named Parameters can now be prefixed by $ or @ in a query.

Documentation Link 1

In the Identifier section here - https://docs.couchbase.com/server/current/settings/query-settings.html#identifier

change:

Syntax:

$<identifier>

or 

@<identifier>

And in the first point of the bulleted list add -

1. The $ or @ character

Documentation Link 2

In the CBQ shell, named parameters can be prefixed by -$ or -@ now. 

In https://docs.couchbase.com/server/current/tools/cbq-shell.html#setting-variable-values change:

In the row for Named Parameters and n the column “Prefix” add:

-$

Or

-@

Documentation Link 3

https://docs.couchbase.com/server/current/tools/cbq-shell.html#handling-named-parameters

Change:

.... For each named parameter, prefix the variable name with -$ or -@...

Modify the example to include the -@ prefix as well. 

Example:

cbq> \SET -$r 9.5;

cbq> \SET -@date "1-1-2016";