docs: fix `v check-md .` on macos

doc/docs.md

@@ -2117,7 +2117,7 @@ They must do so explicitly by listing all variables that are inherited.
 > Warning: currently works on Unix-based, x64 architectures only.
 Some work is in progress to make closures work on Windows, then other architectures.
 
-```v
+```v oksyntax
 my_int := 1
 my_closure := fn [my_int] () {
 	println(my_int)
@@ -2129,7 +2129,7 @@ Inherited variables are copied when the anonymous function is created.
 This means that if the original variable is modified after the creation of the function,
 the modification won't be reflected in the function.
 
-```v
+```v oksyntax
 mut i := 1
 func := fn [i] () int {
 	return i
@@ -2142,7 +2142,7 @@ println(func() == 1) // still true
 However, the variable can be modified inside the anonymous function.
 The change won't be reflected outside, but will be in the later function calls.
 
-```v
+```v oksyntax
 fn new_counter() fn () int {
 	mut i := 0
 	return fn [mut i] () int {
@@ -2161,7 +2161,7 @@ If you need the value to be modified outside the function, use a reference.
 **Warning**: _you need to make sure the reference is always valid,
 otherwise this can result in undefined behavior._
 
-```v
+```v oksyntax
 mut i := 0
 mut ref := &i
 print_counter := fn [ref] () {