Update NativeLibrary.GetExport/TryGetExport remarks (#7342)

Author: elinor-fung

xml/System.Runtime.InteropServices/NativeLibrary.xml

@@ -76,14 +76,16 @@
         <summary>Gets the address of an exported symbol.</summary>
         <returns>The address of the symbol.</returns>
         <remarks>
-          <format type="text/markdown"><![CDATA[  
+          <format type="text/markdown"><![CDATA[
 
 This is a simple wrapper around OS calls and does not perform any name mangling.
 
+Calling this method with an invalid `handle` parameter other than <xref:System.IntPtr.Zero?displayProperty=nameWithType> is not supported and will result in undefined behaviour.
+
          ]]></format>
         </remarks>
         <exception cref="T:System.ArgumentNullException">
-          <paramref name="handle" /> or <paramref name="name" /> is <see langword="null" />.</exception>
+          <paramref name="handle" /> is <see cref="F:System.IntPtr.Zero" /> or <paramref name="name" /> is <see langword="null" />.</exception>
         <exception cref="T:System.EntryPointNotFoundException">The symbol is not found.</exception>
       </Docs>
     </Member>
@@ -149,7 +151,7 @@ This is a simple wrapper around OS calls and does not perform any name mangling.
         <summary>Provides a high-level API for loading a native library.</summary>
         <returns>The OS handle for the loaded library.</returns>
         <remarks>
-          <format type="text/markdown"><![CDATA[  
+          <format type="text/markdown"><![CDATA[
 
 Given a library name, this method searches specific paths based on the  runtime configuration, input parameters, and attributes of the calling assembly. If the `searchPath` parameter is non-null, the flags in this enumeration are used. Otherwise, the flags specified by the <xref:System.Runtime.InteropServices.DefaultDllImportSearchPathsAttribute> on the calling assembly, if any are present, are used. This method does not invoke the resolver registered using <xref:System.Runtime.InteropServices.NativeLibrary.SetDllImportResolver(System.Reflection.Assembly,System.Runtime.InteropServices.DllImportResolver)>
 method. Starting with .NET 5, this method does invoke the <xref:System.Runtime.Loader.AssemblyLoadContext.LoadUnmanagedDll%2A?displayProperty=nameWithType> method and the <xref:System.Runtime.Loader.AssemblyLoadContext.ResolvingUnmanagedDll?displayProperty=nameWithType> event.
@@ -191,10 +193,10 @@ method. Starting with .NET 5, this method does invoke the <xref:System.Runtime.L
         <param name="resolver">The resolver callback to register.</param>
         <summary>Sets a callback for resolving native library imports from an assembly.</summary>
         <remarks>
-          <format type="text/markdown"><![CDATA[  
+          <format type="text/markdown"><![CDATA[
 
 This per-assembly resolver is the first attempt to resolve native library loads initiated by this assembly.
- 
+
 The callers of this method should register the resolver for their own assemblies only.
 
 Only one resolver can be registered per assembly. Trying to register a second resolver fails with an <xref:System.InvalidOperationException>.
@@ -235,10 +237,18 @@ Only one resolver can be registered per assembly. Trying to register a second re
         <param name="address">When the method returns, contains the symbol address, if it exists.</param>
         <summary>Gets the address of an exported symbol and returns a value that indicates whether the method call succeeded.</summary>
         <returns>
-          <see langword="true" /> if the method returned successfully; otherwise, <see langword="false" />.</returns>
-        <remarks>To be added.</remarks>
+          <see langword="true" /> if the address of the exported symbol was found successfully; otherwise, <see langword="false" />.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+This is a simple wrapper around OS calls and does not perform any name mangling.
+
+Calling this method with a invalid `handle` parameter other than <xref:System.IntPtr.Zero?displayProperty=nameWithType> is not supported and will result in undefined behaviour.
+
+         ]]></format>
+        </remarks>
         <exception cref="T:System.ArgumentNullException">
-          <paramref name="handle" /> or <paramref name="name" /> is <see langword="null" />.</exception>
+          <paramref name="handle" /> is <see cref="F:System.IntPtr.Zero" /> or <paramref name="name" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
     <Member MemberName="TryLoad">
@@ -268,7 +278,7 @@ Only one resolver can be registered per assembly. Trying to register a second re
         <param name="handle">When the method returns, the OS handle of the loaded native library.</param>
         <summary>Provides a simple API for loading a native library and returns a value that indicates whether the operation succeeded.</summary>
         <returns>
-          <see langword="true" /> if the native library was loaded successful; otherwise, <see langword="false" />.</returns>
+          <see langword="true" /> if the native library was loaded successfully; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="libraryPath" /> is <see langword="null" />.</exception>
@@ -305,7 +315,7 @@ Only one resolver can be registered per assembly. Trying to register a second re
         <param name="handle">When the method returns, the OS handle of the loaded native library.</param>
         <summary>Provides a high-level API that loads a native library and returns a value that indicates whether the operation succeeded.</summary>
         <returns>
-          <see langword="true" /> if the load operation was successful; otherwise, <see langword="false" />.</returns>
+          <see langword="true" /> if the native library was loaded successfully; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="libraryPath" /> or <paramref name="assembly" /> is <see langword="null" />.</exception>