dcb: improve enable_trace documentation

Author: tmplt

src/peripheral/dcb.rs

@@ -3,6 +3,8 @@
 use volatile_register::{RW, WO};
 
 use crate::peripheral::DCB;
+#[allow(unused_imports)]
+use crate::peripheral::{DWT, ITM};
 use core::ptr;
 
 const DCB_DEMCR_TRCENA: u32 = 1 << 24;
@@ -22,10 +24,7 @@ pub struct RegisterBlock {
 }
 
 impl DCB {
-    /// Enables TRACE. This is for example required by the
-    /// `peripheral::DWT` cycle counter to work properly.
-    /// As by STM documentation, this flag is not reset on
-    /// soft-reset, only on power reset.
+    /// Global enable for all [`DWT`] and [`ITM`] features.
     ///
     /// Note: vendor-specific registers may have to be set to completely
     /// enable tracing. For example, on the STM32F401RE, `TRACE_MODE`