Added *.sublime-workspace to gitignore blueprint

[LJNielsenDk]

According to https://www.sublimetext.com/docs/3/projects.html :
"Projects in Sublime Text are made up of two files: the .sublime-project
file, which contains the project definition, and the .sublime-workspace
file, which contains user specific data, such as the open files and the
modifications to each.

As a general rule, the .sublime-project file would be checked into
version control, while the .sublime-workspace file would not."

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[LJNielsenDk]

I signed it!

[googlebot]

CLAs look good, thanks!

[hansl]

LGTM.

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