Update PKEY2005.md

PKEY2005.md

@@ -63,7 +63,7 @@ This section is devoted to describing the specifics of PKEY2005's validation mec
 
 The binary serialzed form of a PKEY2005 public key is as follows, given in [ImHex Pattern Language](https://docs.werwolv.net/pattern-language/).
 
-```
+```c
 u8 size_bignum @ 0x15;
 
 // Bignums are stored in little endian order