Improve Half docs a bit (#6663)

Author: gewarren

xml/System/Half.xml

@@ -34,8 +34,19 @@
     </Attribute>
   </Attributes>
   <Docs>
-    <summary>An IEEE 754 compliant <see langword="float16" /> type.</summary>
-    <remarks>To be added.</remarks>
+    <summary>Represents a half-precision floating-point number.</summary>
+    <remarks>
+      <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The <xref:System.Half> value type represents a half-precision 16-bit number with values ranging from negative 65,504 to positive 65,504, as well as positive or negative zero, <xref:System.Half.PositiveInfinity>, <xref:System.Half.NegativeInfinity>, and not a number (<xref:System.Half.NaN>).
+
+This is an IEEE 754-compliant <see langword="float16" /> type.
+
+]]></format>
+    </remarks>
+    <seealso cref="T:System.Single" />
   </Docs>
   <Members>
     <Member MemberName="CompareTo">

xml/System/Single.xml

@@ -87,17 +87,17 @@
 ## Remarks  
  The <xref:System.Single> value type represents a single-precision 32-bit number with values ranging from negative 3.402823e38 to positive 3.402823e38, as well as positive or negative zero, <xref:System.Single.PositiveInfinity>, <xref:System.Single.NegativeInfinity>, and not a number (<xref:System.Single.NaN>). It is intended to represent values that are extremely large (such as distances between planets or galaxies) or extremely small (such as the molecular mass of a substance in kilograms) and that often are imprecise (such as the distance from earth to another solar system). The <xref:System.Single> type complies with the IEC 60559:1989 (IEEE 754) standard for binary floating-point arithmetic.  
   
- This topic consists of the following sections:  
+ This article consists of the following sections:  
   
--   [Floating-point representation and precision](#Precision)  
+- [Floating-point representation and precision](#Precision)  
   
--   [Testing for equality](#Equality)  
+- [Testing for equality](#Equality)  
   
--   [Floating-point values and exceptions](#Exceptions)  
+- [Floating-point values and exceptions](#Exceptions)  
   
--   [Type conversion and the Single structure](#Conversion)  
+- [Type conversion and the Single structure](#Conversion)  
   
--   [Floating-point functionality](#Functionality)  
+- [Floating-point functionality](#Functionality)  
   
  <xref:System.Single?displayProperty=nameWithType> provides methods to compare instances of this type, to convert the value of an instance to its string representation, and to convert the string representation of a number to an instance of this type. For information about how format specification codes control the string representation of value types, see [Formatting Types](/dotnet/standard/base-types/formatting-types), [Standard Numeric Format Strings](/dotnet/standard/base-types/standard-numeric-format-strings), and [Custom Numeric Format Strings](/dotnet/standard/base-types/custom-numeric-format-strings).