[skip changelog] Add missing file extensions to Sketch specifications docs

Author: silvanocerza

docs/sketch-specification.md

@@ -35,7 +35,7 @@ The following extensions are supported:
 - .cpp - C++ files.
 - .c - C Files.
 - .S - Assembly language files.
-- .h - Header files.
+- .h, .tpp, .ipp - Header files.
 
 For information about how each of these files and other parts of the sketch are used during compilation, see the
 [Sketch build process documentation](sketch-build-process.md).