docs: TSDoc + reference of fulfillment service (#5761)

www/apps/docs/content/references/services/interfaces/ITaxService.mdx

@@ -12,13 +12,13 @@ items and shipping methods.
 
 ## Methods
 
-#### getTaxLines
+### getTaxLines
 
 `**getTaxLines**(itemLines, shippingLines, context): Promise<[ProviderTaxLine](../types/ProviderTaxLine.mdx)[]>`
 
 Retrieves the numerical tax lines for a calculation context.
 
-##### Parameters
+#### Parameters
 
 <ParameterTypes parameters={[
   {
@@ -50,7 +50,7 @@ Retrieves the numerical tax lines for a calculation context.
   }
 ]} />
 
-##### Returns
+#### Returns
 
 Promise&#60;[ProviderTaxLine](../types/ProviderTaxLine.mdx)[]&#62;