Add TFM for .NET nanoFramework (#45973)

Author: josesimoes

docs/standard/frameworks.md

@@ -42,6 +42,7 @@ A target framework is typically referenced by a TFM. The following table shows t
 | .NET Standard              | netstandard1.0<br>netstandard1.1<br>netstandard1.2<br>netstandard1.3<br>netstandard1.4<br>netstandard1.5<br>netstandard1.6<br>netstandard2.0<br>netstandard2.1 |
 | .NET Framework             | net11<br>net20<br>net35<br>net40<br>net403<br>net45<br>net451<br>net452<br>net46<br>net461<br>net462<br>net47<br>net471<br>net472<br>net48<br>net481 |
 | Windows Store              | netcore [netcore45]<br>netcore45 [win] [win8]<br>netcore451 [win81] |
+| .NET nanoFramework         | netnano1.0 |
 | .NET Micro Framework       | netmf |
 | Silverlight                | sl4<br>sl5 |
 | Windows Phone              | wp [wp7]<br>wp7<br>wp75<br>wp8<br>wp81<br>wpa81 |