updated README

Author: dmalan

README.md

@@ -24,13 +24,14 @@ s = cs50.get_string();
 
 1. Run `cli50` in `python-cs50`.
 1. Run `sudo su -`.
+1. Run `apt update`.
 1. Run `apt install -y libmysqlclient-dev mysql-server postgresql`.
 1. Run `pip3 install mysqlclient psycopg2-binary`.
 1. In `/etc/mysql/mysql.conf.d/mysqld.cnf`, add `skip-grant-tables` under `[mysqld]`.
 1. In `/etc/profile.d/cli.sh`, remove `valgrind` function for now.
 1. Run `service mysql start`.
 1. Run `mysql -e 'CREATE DATABASE IF NOT EXISTS test;'`.
-1. In `/etc/postgresql/12/main/pg_hba.conf, change:
+1. In `/etc/postgresql/12/main/pg_hba.conf`, change:
    ```
    local   all             postgres                                peer
    host    all             all             127.0.0.1/32            md5