Keyboards: Move the other Sentraq keyboards into the sentraq vendor directory (#5052)

* Moving sentraq keyboards to sentraq subdirectory.

* Updating readme markdown to correct make commands.

* Updating s60_x references to point to the new vendor subdirectory.

* Fixed stripped spaces in markdown.

* Updated help information in s60_x readme and linked to additional documentation.

keyboards/sentraq/s65_x/s65_x.c

@@ -0,0 +1,18 @@
+#include "s65_x.h"
+
+void matrix_init_kb(void) {
+  // put your keyboard start-up code here
+  // runs once when the firmware starts up
+  matrix_init_user();
+};
+
+void matrix_scan_kb(void) {
+  // put your looping keyboard code here
+  // runs every cycle (a lot)
+  matrix_scan_user();
+};
+
+void led_set_kb(uint8_t usb_led) {
+  // put your keyboard LED indicator (ex: Caps Lock LED) toggling code here
+  led_set_user(usb_led);
+}