[docs] Add missing docs to enum fields (NFC) (#6150)

Co-authored-by: Tyler Veness <calcmogul@gmail.com>

wpilibc/src/main/native/include/frc/counter/EdgeConfiguration.h

@@ -5,10 +5,17 @@
 #pragma once
 
 namespace frc {
+/**
+ * Edge configuration.
+ */
 enum class EdgeConfiguration {
+  /// No edge configuration (neither rising nor falling).
   kNone = 0,
+  /// Rising edge configuration.
   kRisingEdge = 0x1,
+  /// Falling edge configuration.
   kFallingEdge = 0x2,
+  /// Both rising and falling edges configuration.
   kBoth = 0x3
 };
 }  // namespace frc