[FIX] doc: escape URL

The ampersand (&) needs to be html encoded to be evaluated correctly

Cherry-picked from odoo/odoo#46526
Courtesy of Olaf
Closes odoo/odoo#46526

closes odoo/odoo#50852

X-original-commit: 28b977d4702cd64290c5e48f39c8df2ad9819483
Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

doc/reference/reports.rst

@@ -206,7 +206,7 @@ More parameters can be passed as a query string
 .. code-block:: html
 
     <img t-att-src="'/report/barcode/?
-        type=%s&value=%s&width=%s&height=%s'%('QR', 'text', 200, 200)"/>
+        type=%s&amp;value=%s&amp;width=%s&amp;height=%s'%('QR', 'text', 200, 200)"/>
 
 
 Useful Remarks