(#156)

Added words to the Guide about platform descriptions and simulation
output

doc/guide.md

@@ -6,8 +6,31 @@ Guide                        {#guide}
 @WRENCHInternalDoc  <div class="doc-type">Internal Documentation</div><div class="doc-link">Other: <a href="../user/guide.html">User</a> -  <a href="../developer/guide.html">Developer</a></div> @endWRENCHDoc
 
 
+This page provides pointers to high-level information for WRENCH users who
+want to build simulators. The examples provided  in the  ```example/```
+directory are a great first start. This page goes further by detailing what
+possibilities are available to users beyond what  is shown in the examples.
 
-WRENCH currently provide the following (simulated) CyberInfrastructure Service implementations:
+---
+
+## Simulated Platform Hardware Configurations
+
+A WRENCH simulator must specify the hardware configuration of the platform
+to be simulator (i.e., compute resources, storage resources, network
+resources). WRENCH does not do anything specific and accepts any valid
+[SimGrid platform description in
+XML](https://simgrid.org/doc/latest/platform.html).  The documentation is
+extensive, as many options are possible. We strongly suggest users to
+inspect the platform  files provided  with the  WRENCH examples (in
+directory ```examples/simple-example/platform_files/```). These  files are
+simply passed to the ```wrench::Simulation::instantiatePlatform()```
+method.
+
+---
+
+## Simulated CyberInfrastructure Services
+
+A WRENCH simulation consists in a WMS  (Workflow Management System) that interacts with CyberInfrastructure Service. Several such (simulated) services are implemented in WRENCH and can thus be instantiated on the simulation platform out-of-the-box.  The examples in the ```examples``` directory showcase the use of some of these services, but there are others! WRENCH currently provide the following CyberInfrastructure services:
 
 
 1. Compute Services
@@ -27,3 +50,24 @@ WRENCH currently provide the following (simulated) CyberInfrastructure Service i
     1. [Network Proximity Service](@ref guide-networkproximity)
 
 ---
+
+## Simulation Output
+
+The goal of any simulator is to generate output that describes a simulated
+execution, the outcomes of which can be analyzed for whatever purposes. The
+class ```wrench::SimulationOutput``` contains all relevant information
+(once the simulation has completed). This information can be accessed via
+this class' API (see the relevant documentation in the API Reference
+section). Note that there are also  methods to configure the type  and amount of
+output generated (see the
+```wrench::SimulationOutput::enable*Timestamps()``` methods).
+
+The simulation output can be exported to a JSON file,  using one of the
+```wrench::SimulationOutput::dump*JSON()``` methods. See the documentation of each method to see the structure of the JSON output, in case  you want to parse/process the JSON yourself. Alternately, you  can use the 
+**WRENCH dashboard** to open the JSON and gain access to interactive  visualization/inspection tools. To do so simple  run ```tools/wrench/wrench-dashboard```.
+
+
+
+
+---
+