Use the Atom package manager and search for "linter-spell-pretext", or run
apm install linter-spell-pretext from the command line.
This package relies upon linter-spell and it must therefore be installed.
The package scans the file for language tags like
to determine the appropriate dictionary.
Please note that this package is in an alpha state.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.