*.do scripts are always identified as Stata even when they should be Tcl

[jordancarlin]

*.do is a common extension for Tcl scripts in the hardware design world. Currently, these Tcl scripts are always identified as Stata, even though Tcl is supported by github-linguist. I've included several examples below. It would be great if we could figure out a heuristic to distinguish these from Stata.

Simple *.do Tcl script: https://github.com/openhwgroup/cvw-arch-verif/blob/fed3feef3ed7c334a509c1069dbe63086e384052/bin/cvw-arch-verif.do#L4
More complex *.do Tcl script: https://github.com/openhwgroup/cvw/blob/a076beac44ced477fd2f2b57dc0ab8867b87beb6/sim/questa/wally.do
Alternative common form for Tcl *.do script to control waveforms: https://github.com/pulp-platform/pulp_cluster/blob/caaa9735346bee71b51d1fe6ba526743bc41e135/wave.do#L3