Add remarks to AssemblyLoadContext load methods documenting default context probing behavior (#12236)

Author: Copilot

xml/System.Runtime.Loader/AssemblyLoadContext.xml

@@ -691,7 +691,15 @@ Each <xref:System.Runtime.Loader.AssemblyLoadContext> can load only:
         <param name="assemblyPath">The fully qualified path of the file to load.</param>
         <summary>Loads the contents of an assembly file on the specified path.</summary>
         <returns>The loaded assembly.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+When this method is called on the <xref:System.Runtime.Loader.AssemblyLoadContext.Default> context, if the assembly name matches an assembly that's part of the default probing path, the assembly from the default probing path is loaded instead of the assembly at the specified path. For more information about default probing, see [Managed assembly loading algorithm](/dotnet/core/dependency-loading/loading-managed).
+
+ ]]></format>
+        </remarks>
         <exception cref="T:System.ArgumentException">The <paramref name="assemblyPath" /> argument is not an absolute path.</exception>
         <exception cref="T:System.ArgumentNullException">The <paramref name="assemblyPath" /> argument is <see langword="null" />.</exception>
         <exception cref="T:System.IO.FileLoadException">A file that was found could not be loaded.</exception>
@@ -813,7 +821,15 @@ Each <xref:System.Runtime.Loader.AssemblyLoadContext> can load only:
         <param name="assembly">A byte array that is a COFF-based image containing a managed assembly.</param>
         <summary>Loads the assembly with a common object file format (COFF)-based image containing a managed assembly.</summary>
         <returns>The loaded assembly.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+When this method is called on the <xref:System.Runtime.Loader.AssemblyLoadContext.Default> context, if the assembly name matches an assembly that's part of the default probing path, the assembly from the default probing path is loaded instead of the assembly from the stream. For more information about default probing, see [Managed assembly loading algorithm](/dotnet/core/dependency-loading/loading-managed).
+
+ ]]></format>
+        </remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="assembly" /> is <see langword="null" />.</exception>
         <exception cref="T:System.BadImageFormatException">
@@ -873,7 +889,15 @@ Each <xref:System.Runtime.Loader.AssemblyLoadContext> can load only:
         <param name="assemblySymbols">A byte array that contains the raw bytes representing the symbols for the assembly.</param>
         <summary>Loads the assembly with a common object file format (COFF)-based image containing a managed assembly, optionally including symbols for the assembly.</summary>
         <returns>The loaded assembly.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+When this method is called on the <xref:System.Runtime.Loader.AssemblyLoadContext.Default> context, if the assembly name matches an assembly that's part of the default probing path, the assembly from the default probing path is loaded instead of the assembly from the stream. For more information about default probing, see [Managed assembly loading algorithm](/dotnet/core/dependency-loading/loading-managed).
+
+ ]]></format>
+        </remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="assembly" /> is <see langword="null" />.</exception>
         <exception cref="T:System.BadImageFormatException">