README.md: update macOS instructions

README.md

@@ -37,7 +37,6 @@ curl -sSL https://get.haskellstack.org/ | sh
 git clone https://github.com/gibiansky/IHaskell
 cd IHaskell
 pip3 install -r requirements.txt
-# stack install gtk2hs-buildtools # Disabled for now because gtk2hs-buildtools doesn't work with lts-13 yet
 stack install --fast
 ihaskell install --stack
 ```
@@ -64,12 +63,11 @@ brew install python3 zeromq libmagic cairo pkg-config haskell-stack pango
 git clone https://github.com/gibiansky/IHaskell
 cd IHaskell
 pip3 install -r requirements.txt
-# stack install gtk2hs-buildtools # Disabled for now because gtk2hs-buildtools doesn't work with lts-13 yet
 stack install --fast
 ihaskell install --stack
 ```
 
-If you have Homebrew installed to a custom location, you'd need to specify `--extra-include-dirs ${HOMEBREW_PREFIX}/include --extra-lib-dir ${HOMEBREW_PREFIX}/lib` to the `stack` command.
+If you have Homebrew installed to a location that `stack` does not expect (e.g. `/opt/homebrew`), you'd need to specify `--extra-include-dirs ${HOMEBREW_PREFIX}/include --extra-lib-dir ${HOMEBREW_PREFIX}/lib` to the `stack` command.
 
 Run Jupyter.