Make The Compiling for Web documentation more obvious - corrected

Thanks for your feedback @eska014, here is a better and corrected version, with no syntax mistakes as far as I can check.

development/compiling/compiling_for_web.rst

@@ -10,7 +10,7 @@ Requirements
 
 To compile export templates for the Web, the following is required:
 
--  `Emscripten <http://emscripten.org/>`__, plus `LLVM <https://llvm.org/>`__ and `Binaryen <https://github.com/WebAssembly/binaryen>`__ if you want to compile for *Webassembly* (Godot 3). The easiest way to install them if they are not up to date in your Linux package manager is to use the `Emscripten SDK <http://emscripten.org/>`__ (Install in a path without spaces, i.e. not on "Program Files")
+-  `Emscripten <http://emscripten.org/>`__: The easiest way to install it, if it's not up to date in your Linux package manager, is to use the `Emscripten SDK <http://emscripten.org/>`__ (Install in a path without spaces, i.e. not on "Program Files")
 -  `Python 2.7+ <https://www.python.org/>`__ (3.0 is untested as of now)
 -  `SCons <http://www.scons.org>`__ build system
 
@@ -20,15 +20,15 @@ Building export templates
 Start a terminal and set the environment variable ``EMSCRIPTEN_ROOT`` to the
 installation directory of Emscripten:
 
--  If you installed Emscripten via the Emscripten SDK, you will declare the variable with a path to your downloaded folder:
+-  If you installed Emscripten via the Emscripten SDK, you will declare the variable with a path to your downloaded folder::
 
     export EMSCRIPTEN_ROOT=~/emsdk/emscripten/master
     
--  If you installed Emscripten via your package manager, you can know the path with the ``em-config`` command
+-  If you installed Emscripten via your package manager, you can know the path with the ``em-config`` command::
 
     em-config EMSCRIPTEN_ROOT
 
-   So you will declare the variable as for example:
+   So you will declare the variable as for example::
 
     export EMSCRIPTEN_ROOT=/usr/lib/emscripten
     
@@ -108,7 +108,7 @@ These commands will build WebAssembly export templates in either release or
 debug mode. The generated files' names contain ``.webassembly`` as an
 additional file suffix before the extension.
 
-If it's not compiling, check if you have properly installed everything, and if ``LLVM_ROOT`` and ``BINARYEN_ROOT`` variables are defined in the ``~/.emscripten`` file. You can define the ``BINARYEN_ROOT`` path manually in this file if you already installed it and want to avoid Scons to compile it from ports during template compilation.
+If it's not compiling, check if you have properly installed everything, and if ``LLVM_ROOT`` and ``BINARYEN_ROOT`` variables are defined in the ``~/.emscripten`` file. You can define the ``BINARYEN_ROOT`` path manually in this file if you already installed Binaryen an other way and want to avoid SCons to compile it from ports during template compilation. Emscripten SDK comes with its own fork of LLVM called fastcomp, which has the JSBackend needed for asm.js and asm2wasm, so the ``LLVM_ROOT`` path must lead to an ``/emscripten-fastcomp`` directory.
 
 Finally, the WebAssembly templates are renamed to ``webassembly_release.zip``
 and ``webassembly_debug.zip``::