stlink: add st-info page

pages/common/st-info.md

@@ -0,0 +1,15 @@
+# st-info
+
+> Provides information about connected STLink and STM32 devices.
+
+- Display about of program memory available:
+
+`st-info --flash`
+
+- Display about of sram memory available:
+
+`st-info --sram`
+
+- Display summarized information of the device:
+
+`st-info --probe`