Fix a small typo in README.md

Change-Id: I746c4a6ce31a0997ba7fe5495673cce3cf9268c3
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>

GitOrigin-RevId: 96f59160d45ca3aba9b23061ddf7df1aca862376

README.md

@@ -133,7 +133,7 @@ You can accomplish common crypto operations such as data encryption, digital
 signatures, etc. with only a few lines of code. For example, to encrypt a
 piece of data using authenticated encryption you need only 3 lines of code:
 
-``
+```
 // 1. Read a keyset from some storage system
 KeysetHandle keysetHandle = KeysetHandle.newHandle(bytes);
 
@@ -142,7 +142,7 @@ Aead aead = AeadFactory.getPrimitive(keysetHandle);
 
 // 3. Use the primitive.
 byte[] ciphertext = aead.encrypt(plaintext, associatedData);
-``
+```
 
 ### Composability