docs: fix database name and change text decoration for driver names

Author: kenjis

user_guide_src/source/intro/requirements.rst

@@ -49,11 +49,11 @@ Supported Databases
 A database is required for most web application programming.
 Currently supported databases are:
 
-  - MySQL via the *MySQLi* driver (version 5.1 and above only)
-  - PostgreSQL via the *Postgre* driver
-  - SQLite3 via the *SQLite3* driver
-  - MSSQL via the *SQLSRV* driver (version 2005 and above only)
-  - Oracle via the *OCI8* driver (version 12.1 and above only)
+  - MySQL via the ``MySQLi`` driver (version 5.1 and above only)
+  - PostgreSQL via the ``Postgre`` driver
+  - SQLite3 via the ``SQLite3`` driver
+  - Microsoft SQL Server via the ``SQLSRV`` driver (version 2005 and above only)
+  - Oracle Database via the ``OCI8`` driver (version 12.1 and above only)
 
 Not all of the drivers have been converted/rewritten for CodeIgniter4.
 The list below shows the outstanding ones.