doc: boards: fix typo in CH32V303VCT6-EVT board name

The name of the boards was incorrect in the documentation,
Fix the name of the board according to the official name.

Signed-off-by: Miguel Gazquez <miguel.gazquez@bootlin.com>

boards/wch/ch32v303vct6_evt/doc/index.rst

@@ -3,7 +3,7 @@
 Overview
 ********
 
-The `WCH`_ CH3V303VCT6_EVT hardware provides support for QingKe V4F 32-bit RISC-V
+The `WCH`_ CH32V303VCT6-EVT hardware provides support for QingKe V4F 32-bit RISC-V
 processor.
 
 The `WCH webpage on CH32V303`_ contains
@@ -12,7 +12,7 @@ the processor's information and the datasheet.
 Hardware
 ********
 
-The QingKe V4F 32-bit RISC-V processor of the WCH CH32V303VCT6_EVT is clocked by an external
+The QingKe V4F 32-bit RISC-V processor of the WCH CH32V303VCT6-EVT is clocked by an external
 32 MHz crystal or the internal 8 MHz oscillator and runs up to 144 MHz.
 The CH32V303 SoC features 8 USART, 4 GPIO ports, 3 SPI, 2 I2C, 2 ADC, RTC,
 CAN, USB Host/Device, and 4 OPA.