Fix documentation warnings generated by JavaDoc (NFC) (#3428)

Some C++ Doxygen comments were updated to reflect any wording changes.

See `rg "(@return|@param \w+) TODO" | less` for list of incomplete docs.

wpiutil/src/main/native/include/wpi/Endian.h

@@ -38,7 +38,7 @@ enum {aligned = 0, unaligned = 1};
 
 namespace detail {
 
-/// ::value is either alignment, or alignof(T) if alignment is 0.
+// value is either alignment, or alignof(T) if alignment is 0.
 template<class T, int alignment>
 struct PickAlignment {
  enum { value = alignment == 0 ? alignof(T) : alignment };

wpiutil/src/main/native/include/wpi/json.h

@@ -7562,7 +7562,7 @@ class json
                                    const bool strict = true);
 
     /*!
-    @copydoc from_msgpack(raw_istream, const bool)
+    @copydoc from_msgpack(raw_istream&, const bool)
     */
     static json from_msgpack(span<const uint8_t> arr, const bool strict = true);