Update README.md

[waddlaw]

λ> make build-doc-hie-8.6.3
stack --stack-yaml=stack-hie-8.6.3.yaml exec hoogle generate
Could not parse '/home/guchi/.local/share/haskell-ide-engine/stack-hie-8.6.3.yaml':
YAML exception:
Yaml file not found: /home/guchi/.local/share/haskell-ide-engine/stack-hie-8.6.3.yaml
See http://docs.haskellstack.org/en/stable/yaml_configuration/
Makefile:66: recipe for target 'build-doc-hie-8.6.3' failed
make: *** [build-doc-hie-8.6.3] Error 1

λ> make build-doc-8.6.3
stack --stack-yaml=stack-8.6.3.yaml exec hoogle generate
Starting generate
...

[fendor]

Thank you, replaced the string too eagerly.