"Unix" -> "Unicode" in GetUnicodeCategory Remarks (#3075)

The term "the Unix Standard" is incorrect and should instead be "the Unicode Standard". I fixed 4 instances of this mistake, all in "GetUnicodeCategory". This mistake appears to have been introduced in the following commit on March 21, 2017:

cd8c569#diff-206ae69d9a4bfeaf7052220b8e8cde2a

Author: srutzky

xml/System/Char.xml

@@ -969,7 +969,7 @@ When a managed <xref:System.Char> type, which is represented as a Unicode UTF-16
 ## Remarks  
  The <xref:System.Char.GetUnicodeCategory%2A?displayProperty=nameWithType> method does not always return the same <xref:System.Globalization.UnicodeCategory> value as the <xref:System.Globalization.CharUnicodeInfo.GetUnicodeCategory%28System.Char%29?displayProperty=nameWithType> method when it is passed a particular character as a parameter. The <xref:System.Globalization.CharUnicodeInfo.GetUnicodeCategory%28System.Char%29?displayProperty=nameWithType> method is designed to reflect the current version of the Unicode standard. In contrast, although the <xref:System.Char.GetUnicodeCategory%2A?displayProperty=nameWithType> method usually reflects the current version of the Unicode standard, it may return a character's category based on a previous version of the standard or it may return a category that differs from the current standard in order to preserve backward compatibility. As a result, we recommend that you use the <xref:System.Globalization.CharUnicodeInfo.GetUnicodeCategory%28System.Char%29?displayProperty=nameWithType> method instead of <xref:System.Char.GetUnicodeCategory%28System.Char%29?displayProperty=nameWithType>.  
   
- Starting with the [!INCLUDE[net_v462](~/includes/net-v462-md.md)], Unicode characters are classified based on [The Unix Standard, Version 8.0.0](https://www.unicode.org/versions/Unicode8.0.0/). In versions of the .NET Framework from the [!INCLUDE[net_v40_long](~/includes/net-v40-long-md.md)] to  the [!INCLUDE[net_v461](~/includes/net-v461-md.md)], they are classified based on [The Unix Standard, Version 6.3.0](https://www.unicode.org/versions/Unicode6.3.0/).  
+ Starting with the [!INCLUDE[net_v462](~/includes/net-v462-md.md)], Unicode characters are classified based on [The Unicode Standard, Version 8.0.0](https://www.unicode.org/versions/Unicode8.0.0/). In versions of the .NET Framework from the [!INCLUDE[net_v40_long](~/includes/net-v40-long-md.md)] to  the [!INCLUDE[net_v461](~/includes/net-v461-md.md)], they are classified based on [The Unicode Standard, Version 6.3.0](https://www.unicode.org/versions/Unicode6.3.0/).  
   
    
   
@@ -1035,7 +1035,7 @@ When a managed <xref:System.Char> type, which is represented as a Unicode UTF-16
   
  The <xref:System.Char.GetUnicodeCategory%2A?displayProperty=nameWithType> method does not always return the same <xref:System.Globalization.UnicodeCategory> value as the <xref:System.Globalization.CharUnicodeInfo.GetUnicodeCategory%28System.String%2CSystem.Int32%29?displayProperty=nameWithType> method when it is passed a particular character as a parameter. The <xref:System.Globalization.CharUnicodeInfo.GetUnicodeCategory%28System.String%2CSystem.Int32%29?displayProperty=nameWithType> method is designed to reflect the current version of the Unicode standard. In contrast, although the <xref:System.Char.GetUnicodeCategory%2A?displayProperty=nameWithType> method usually reflects the current version of the Unicode standard, it may return a character's category based on a previous version of the standard or it may return a category that differs from the current standard in order to preserve backward compatibility. As a result, we recommend that you use the <xref:System.Globalization.CharUnicodeInfo.GetUnicodeCategory%28System.Char%29?displayProperty=nameWithType> method instead of <xref:System.Char.GetUnicodeCategory%28System.String%2CSystem.Int32%29?displayProperty=nameWithType>.  
   
- Starting with the [!INCLUDE[net_v462](~/includes/net-v462-md.md)], Unicode characters are classified based on [The Unix Standard, Version 8.0.0](https://www.unicode.org/versions/Unicode8.0.0/). In versions of the .NET Framework from the [!INCLUDE[net_v40_long](~/includes/net-v40-long-md.md)] to  the [!INCLUDE[net_v461](~/includes/net-v461-md.md)], they are classified based on [The Unix Standard, Version 6.3.0](https://www.unicode.org/versions/Unicode6.3.0/).  
+ Starting with the [!INCLUDE[net_v462](~/includes/net-v462-md.md)], Unicode characters are classified based on [The Unicode Standard, Version 8.0.0](https://www.unicode.org/versions/Unicode8.0.0/). In versions of the .NET Framework from the [!INCLUDE[net_v40_long](~/includes/net-v40-long-md.md)] to  the [!INCLUDE[net_v461](~/includes/net-v461-md.md)], they are classified based on [The Unicode Standard, Version 6.3.0](https://www.unicode.org/versions/Unicode6.3.0/).