boards: 01space: adopt new zephyr:board directive and role

This updates the documentation of all the 01space boards to use
the new `zephyr:board::` directive.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

boards/01space/esp32c3_042_oled/doc/index.rst

@@ -1,7 +1,4 @@
-.. _01space_esp32c3_042_oled:
-
-ESP32C3 0.42 OLED
-#################
+.. zephyr:board:: esp32c3_042_oled
 
 Overview
 ********
@@ -11,12 +8,6 @@ RISC-V WiFi/Bluetooth dual-mode chip.
 
 For more details see the `01space ESP32C3 0.42 OLED`_ Github repo.
 
-.. figure:: img/esp32c3_042_oled.webp
-   :align: center
-   :alt: 01space ESP32C3 0.42 OLED
-
-   01space ESP32C3 0.42 OLED
-
 Hardware
 ********