doc/haskell: document {enable,disable}*Profiling functions

`dontCoverage drv`

: Sets the `doCoverage` argument to `false` for `drv`.

`enableExecutableProfiling drv`

: Sets the `enableExecutableProfiling` argument to `true` for `drv`.

`disableExecutableProfiling drv`

: Sets the `enableExecutableProfiling` argument to `false` for `drv`.

`enableLibraryProfiling drv`

: Sets the `enableLibraryProfiling` argument to `true` for `drv`.

`disableLibraryProfiling drv`

: Sets the `enableLibraryProfiling` argument to `false` for `drv`.

#### Library functions in the Haskell package sets {#haskell-package-set-lib-functions}

Some library functions depend on packages from the Haskell package sets. Thus they are