Change the exclusion instruction in the ReadMe

[CyrilAdelekan]

I tried the instructions with the exclusion

tsuml2 --glob "./src/**/!(*.d|*.spec).ts"

and i got the error

bash: !: event not found

my intension was to exclude any *.test.ts files like the *.d.ts and the *.spec.ts in the instruction

but i find that changing the ! to \! so that the command is

tsuml2 --glob "./src/**/\!(*.d|*.spec).ts"

worked great.