📝 Descibe null checks in obsolete message for equality overloads (#1192)

Fixes #1191

Author: angularsen

CodeGen/Generators/UnitsNetGen/QuantityGenerator.cs

@@ -754,15 +754,15 @@ private void GenerateEqualityAndComparison()
 
         /// <summary>Indicates strict equality of two <see cref=""{_quantity.Name}""/> quantities, where both <see cref=""Value"" /> and <see cref=""Unit"" /> are exactly equal.</summary>
         /// <remarks>Consider using <see cref=""Equals({_quantity.Name}, {_valueType}, ComparisonType)""/> to check equality across different units and to specify a floating-point number error tolerance.</remarks>
-        [Obsolete(""Consider using Equals(Angle, {_valueType}, ComparisonType) to check equality across different units and to specify a floating-point number error tolerance."")]
+        [Obsolete(""For null checks, use `x is null` syntax to not invoke overloads. For quantity comparisons, use Equals(Angle, {_valueType}, ComparisonType) to check equality across different units and to specify a floating-point number error tolerance."")]
         public static bool operator ==({_quantity.Name} left, {_quantity.Name} right)
         {{
             return left.Equals(right);
         }}
 
         /// <summary>Indicates strict inequality of two <see cref=""{_quantity.Name}""/> quantities, where both <see cref=""Value"" /> and <see cref=""Unit"" /> are exactly equal.</summary>
         /// <remarks>Consider using <see cref=""Equals({_quantity.Name}, {_valueType}, ComparisonType)""/> to check equality across different units and to specify a floating-point number error tolerance.</remarks>
-        [Obsolete(""Consider using Equals(Angle, {_valueType}, ComparisonType) to check equality across different units and to specify a floating-point number error tolerance."")]
+        [Obsolete(""For null checks, use `x is not null` syntax to not invoke overloads. For quantity comparisons, use Equals(Angle, {_valueType}, ComparisonType) to check equality across different units and to specify a floating-point number error tolerance."")]
         public static bool operator !=({_quantity.Name} left, {_quantity.Name} right)
         {{
             return !(left == right);