fix spell

change some ap to sum up

docs/develop/data-formats/tl-b-language.mdx

@@ -200,7 +200,7 @@ form `ident:type-expr`, where ident is an identifier with the name of the field
 anonymous fields), and type-expr is the field’s type. The type provided here is a type expression, which may include
 simple types, parametrized types with suitable parameters or complex expressions.
 
-<b>In sum ap all fields defined in type must not be greater than Cell (`1023` bits and `4` refs)</b>
+<b>In sum up all fields defined in type must not be greater than Cell (`1023` bits and `4` refs)</b>
 
 ### Simple types