In error/warning link text, correctly say "error" or "warning"

[mjgpy3]

Pretty simple, I got confused for a second when a warning said

... for more information, or to contribute content related to this error.

This change makes the text say contribute content related to this (error|warning). depending on the level.

e.g.

Error found:
Error in module Main:
Error at /home/michael/dev/contrib/purescript/Foobar.purs line 3, column 8 - line 3, column 13:
  Unknown value (+)
See https://github.com/purescript/purescript/wiki/Error-Code-UnknownValue for more information, or to contribute content related to this error.

and

Compiling Main
Warning found:
Warning in module Main:
Warning in value declaration a:
Warning at /home/michael/dev/contrib/purescript/Foobar.purs line 3, column 1 - line 3, column 8:
    Pattern could not be determined to cover all cases.
    The definition has the following uncovered cases:

    _
See https://github.com/purescript/purescript/wiki/Error-Code-NotExhaustivePattern for more information, or to contribute content related to this warning.

[paf31]

Thanks!