docs: fix some mixed indentation, found by `v check-md .`

doc/docs.md

@@ -374,7 +374,7 @@ In development mode the compiler will warn you that you haven't used the variabl
 In production mode (enabled by passing the `-prod` flag to v – `v -prod foo.v`)
 it will not compile at all (like in Go).
 
-```v failcompile
+```v failcompile nofmt
 fn main() {
 	a := 10
 	if true {
@@ -937,7 +937,7 @@ import crypto.sha256
 import mymod.sha256 as mysha256
 
 fn main() {
-    v_hash := sha256.sum('hi'.bytes()).hex()
+	v_hash := mysha256.sum('hi'.bytes()).hex()
 	my_hash := mysha256.sum('hi'.bytes()).hex()
 	assert my_hash == v_hash
 }
@@ -3026,6 +3026,7 @@ fn main() {
 
 ```v failcompile
 module main
+
 // hello_test.v
 fn test_hello() {
 	assert hello() == 'Hello world'