Add sql highlighting

Installation.md

@@ -103,6 +103,7 @@ The table prefix option is called `tbl`.
 For reference or if you want to create the table schema for yourself (replace
 `prefix_` with your own table prefix):
 
+```sql
 CREATE TABLE prefix_paste (
     dataid CHAR(16) NOT NULL,
     data BLOB,
@@ -132,3 +133,4 @@ For reference or if you want to create the table schema for yourself (replace
     id CHAR(16) NOT NULL, value TEXT, PRIMARY KEY (id)
 );
 INSERT INTO prefix_config VALUES('VERSION', '0.22');
+```