Fix description on non-residential SDLT rate parameter (#1610)

The description incorrectly said "residential property transfers"
for the non-residential purchase SDLT parameter. Fixes #634.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: vahid-ahmadi

changelog.d/634.md

@@ -0,0 +1 @@
+- Fix incorrect description on non-residential SDLT rate parameter (was labelled "residential")

policyengine_uk/parameters/gov/hmrc/stamp_duty/non_residential/purchase.yaml

@@ -19,7 +19,7 @@ brackets:
   threshold:
     2003-07-10: 500000
     2016-09-15: null
-description: Stamp Duty Land Tax progressive rates for residential property transfers
+description: Stamp Duty Land Tax progressive rates for non-residential property transfers
 metadata:
   economy: false
   label: Stamp Duty on non-residential property