Update docs

Author: Doimhneacht

source/campaigns/editor/filters.rst

@@ -996,8 +996,8 @@ This example can be used in ``Email sending condition`` of Advocate Offer Email
 qr\_code
 ........
 
-Converts a string into a QR code. By default, produces an image in SVG format. If HTML format is specified,
-returns an HTML table, which may be useful for inclusion in emails.
+Converts a string into a QR code. By default, produces an image in SVG format. If ``png_base64`` format is specified,
+returns a source for an HTML element, containing a base64-encoded PNG image.
 
 .. code-block:: liquid
 
@@ -1007,8 +1007,8 @@ returns an HTML table, which may be useful for inclusion in emails.
 
 It may take the following arguments:
 
-* ``xdim`` - the width of the narrowest bar in a barcode. Thicker bars are multiples of the xdim. Default value is ``4``.
-* ``format`` - custom format for the result. Only ``html`` is supported.
+* ``xdim`` - the width of the cell in a QR code. Default value is ``4``.
+* ``format`` - custom format for the result. Only ``png_base64`` is supported.
 
 This filter generates a QR code that can be used to encode URLs, text, or coupon codes. The QR code is returned as an SVG image that can be directly embedded in HTML.
 
@@ -1020,13 +1020,11 @@ This filter generates a QR code that can be used to encode URLs, text, or coupon
      {{ coupon.code | qr_code: xdim: 6 }}
    </div>
 
-To return a QR code as an HTML table that can be embedded in email body, use the custom format:
+To return a QR code as a base64-encoded PNG that can be embedded in email body, use the custom format:
 
 .. code-block:: liquid
 
-   <div class="qr-code-container">
-     {{ coupon.code | qr_code: format: 'html' }}
-   </div>
+   <img src="{{ coupon.code | qr_code: format: 'png_base64' }}" />"
 
 |hr|