System.Security.Permissions missing documentation (dotnet#2276)

* Found 4 params in System.Security.Permissions that were undoc'd in dotnet-api-docs but with existing triple slash comments.

* Changed the > and < to the actual symbol

Author: carlossanlop

xml/System.Security.Permissions/PrincipalPermission.xml

@@ -355,7 +355,7 @@
       </Parameters>
       <Docs>
         <param name="o">The <see cref="T:System.Security.Permissions.PrincipalPermission" /> object to compare with the current <see cref="T:System.Security.Permissions.PrincipalPermission" />.</param>
-        <param name="obj">To be added.</param>
+        <param name="obj">The <see cref="T:System.Security.Permissions.PrincipalPermission" /> object to compare with the current <see cref="T:System.Security.Permissions.PrincipalPermission" />.</param>
         <summary>Determines whether the specified <see cref="T:System.Security.Permissions.PrincipalPermission" /> object is equal to the current <see cref="T:System.Security.Permissions.PrincipalPermission" />.</summary>
         <returns>
           <see langword="true" /> if the specified <see cref="T:System.Security.Permissions.PrincipalPermission" /> is equal to the current <see cref="T:System.Security.Permissions.PrincipalPermission" /> object; otherwise, <see langword="false" />.</returns>

xml/System.Security.Permissions/RegistryPermission.xml

@@ -344,7 +344,7 @@
       <Docs>
         <param name="access">One of the <see cref="T:System.Security.Permissions.RegistryPermissionAccess" /> values.</param>
         <param name="actions">One of the <see cref="T:System.Security.AccessControl.AccessControlActions" /> values.</param>
-        <param name="control">To be added.</param>
+        <param name="control">One of the <see cref="T:System.Security.AccessControl.AccessControlActions" /> values.</param>
         <param name="pathList">A list of registry variables (separated by semicolons).</param>
         <summary>Adds access for the specified registry variables to the existing state of the permission, specifying registry permission access and access control actions.</summary>
         <remarks>
@@ -446,7 +446,7 @@
       </Parameters>
       <Docs>
         <param name="elem">The XML encoding to use to reconstruct the permission.</param>
-        <param name="esd">To be added.</param>
+        <param name="esd">The XML encoding to use to reconstruct the permission.</param>
         <summary>Reconstructs a permission with a specified state from an XML encoding.</summary>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">The <paramref name="elem" /> parameter is <see langword="null" />.</exception>

xml/System.Security.Permissions/StrongNamePublicKeyBlob.xml

@@ -115,7 +115,7 @@
       </Parameters>
       <Docs>
         <param name="o">An object containing a public key blob.</param>
-        <param name="obj">To be added.</param>
+        <param name="obj">An object containing a public key blob.</param>
         <summary>Gets or sets a value indicating whether the current public key blob is equal to the specified public key blob.</summary>
         <returns>
           <see langword="true" /> if the public key blob of the current object is equal to the public key blob of the <paramref name="o" /> parameter; otherwise, <see langword="false" />.</returns>