message: Add statement about memory.
diff: @@ -58,6 +58,9 @@ cd pigallery2
  npm install
  ```
  #### 1.2.1-b Install from source
  +
  +**Note:** A build requires a machine with around 2GB or memory.
  +
  ```bash
  cd ~
  wget https://github.com/bpatrik/pigallery2/archive/master.zip
  