message: Update installation docs wrt/ Make parallelism
  Summary: Default the commands to no parallelism. This is more conservative and safer for build machines with less memory. Rewrite the parallelism comment the other way, incrementing the parallelism if enough RAM is available.
diff: @@ -76,10 +76,13 @@ cd redex
  Now, build ReDex using autoconf and make.
  ```
  -autoreconf -ivf && ./configure && make -j
  +autoreconf -ivf && ./configure && make
  sudo make install
  ```
  -If you experience out-of-memory errors, reduce Make parallelism, e.g., to `-j4`.
  +*If your build machine has lots of RAM (on the order of 2-4GB per core), using
  +Make parallelism can speed up the build (e.g., `make -j4`). However, the C++
  +compilers are very memory hungry and this needs to be finely tuned on many
  +systems.*
  ### Experimental: Windows (64-bit) with MSYS2
  @@ -92,9 +95,12 @@ cd redex
  mkdir build-cmake
  cd build-cmake
  cmake -G "MSYS Makefiles" ..
  -make -j
  +make
  ```
  -If you experience out-of-memory errors, reduce Make parallelism, e.g., to `-j4`.
  +*If your build machine has lots of RAM (on the order of 2-4GB per core), using
  +Make parallelism can speed up the build (e.g., `make -j4`). However, the C++
  +compilers are very memory hungry and this needs to be finely tuned on many
  +systems.*
  You may check whether the produced binary seems in a working condition:
  ```
  @@ -171,4 +177,7 @@ Run tests with
  ```
  make -j check
  ```
  -If you experience out-of-memory errors, reduce Make parallelism, e.g., to `-j4`.
  +*If your build machine has lots of RAM (on the order of 2-4GB per core), using
  +Make parallelism can speed up the build and testing (e.g., `make -j4`). However,
  +the C++ compilers are very memory hungry and this needs to be finely tuned on
  +many systems.*
  