Fix some docfx warnings

https://github.com/dotnet/docfx/issues/6995

src/NmeaParser/Gnss/GnssMonitor.cs

@@ -437,7 +437,7 @@ namespace NmeaParser.Gnss
         /// <seealso cref="IsFixValid"/>
         public event EventHandler? LocationLost;
 
-        /// <inheritdoc />
+        /// <summary>Occurs when a property value changes.</summary>
         public event PropertyChangedEventHandler? PropertyChanged;
 
         private void OnPropertyChanged(IEnumerable<string> properties)

src/NmeaParser/Nmea/Gsv.cs

@@ -246,7 +246,10 @@ namespace NmeaParser.Messages
             }
         }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Returns a string that represents the satellite vehicle.
+        /// </summary>
+        /// <returns>A string that represents the satellite vehicle.</returns>
         public override string ToString()
         {
             switch (TalkerId)

src/NmeaParser/Nmea/NmeaMessage.cs

@@ -233,7 +233,10 @@ namespace NmeaParser.Messages
         /// </summary>
         public bool IsProprietary => MessageType[0] == 'P'; //Appendix B
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Returns the original NMEA string that represents this message.
+        /// </summary>
+        /// <returns>An original NMEA string that represents this message.</returns>
         public override string ToString()
         {
             return string.Format(CultureInfo.InvariantCulture, "${0},{1}*{2:X2}", MessageType, string.Join(",", MessageParts), Checksum);
@@ -301,7 +304,11 @@ namespace NmeaParser.Messages
             return TimeSpan.Zero;
         }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Indicates whether the current object is equal to another object of the same type.
+        /// </summary>
+        /// <param name="other">An object to compare with this object.</param>
+        /// <returns><c>true</c> if the current object is equal to the other parameter; otherwise, <c>false</c>.</returns>
         public bool Equals(NmeaMessage other)
         {
             if (other.MessageType != MessageType)

src/NmeaParser/SerialPortDevice.UWP.cs

@@ -68,7 +68,7 @@ namespace NmeaParser
         /// Initializes a new instance of the <see cref="SerialPortDevice" /> class.
         /// </summary>
         /// <param name="device">The serial port.</param>
-        /// <exception cref="System.ArgumentNullException">port</exception>
+        /// <exception cref="ArgumentNullException">port</exception>
         public SerialPortDevice(SerialDevice device)
         {
             if (device == null)