Update doc/how-to-package-haskell-code.rst

Co-authored-by: brandon s allbery kf8nh <[email protected]>

doc/how-to-package-haskell-code.rst

@@ -62,7 +62,7 @@ One of the important questions is whether the package contains a library
 and/or an executable. Libraries are collections of Haskell modules that
 can be re-used by other Haskell libraries and programs, while executables
 are standalone programs. Test suites can both depend on a library or be
-standalonely generated.
+standalone.
 
 For the moment these are the only choices. For more complex packages
 (e.g. a library and multiple executables) the ``.cabal``