[docs] Change c5.4xlarge -> z1d.2xlarge; note Vivado memory usage

deploy/sample-backup-configs/sample_config_build_recipes.ini

@@ -5,6 +5,10 @@
 # edit config_build.ini to actually "turn on" a config to be built when you run
 # buildafi
 
+# Note: For large designs (ones that would fill a EC2.2xlarge/Xilinx VU9P)
+# Vivado uses in excess of 32 GiB. Keep this in mind when selecting a
+# non-default instancetype.
+
 # Single-core, Rocket-based recipes
 
 [firesim-singlecore-nic-l2-lbp]

docs/Advanced-Usage/Manager/Manager-Configuration-Files.rst

@@ -344,7 +344,7 @@ Targets<generating-different-targets>`).
 """""""""""""""""""
 
 This defines the type of instance that the build will run on. Generally, running
-on a ``c5.4xlarge`` is sufficient. In our experience, using more powerful instances
+on a ``z1d.2xlarge`` is sufficient. In our experience, using more powerful instances
 than this provides little gain.
 
 ``deploytriplet``

docs/Building-a-FireSim-AFI.rst

@@ -40,7 +40,10 @@ parallel, with the parameters listed in the relevant section of the
 ``deploy/config_build_recipes.ini`` file. Here you can set parameters of the simulated
 system, and also select the type of instance on which the Vivado build will be
 deployed. From our experimentation, there are diminishing returns using
-anything above a ``c5.4xlarge``, so we default to that.
+anything above a ``z1d.2xlarge``, so we default to that. If you do wish to use a
+different build instance type keep in mind that Vivado will consume in excess
+of 32 GiB for large designs.
+
 
 To start out, let's build a simple design, ``firesim-singlecore-no-nic-lbp``.
 This is a design that has one core, no nic, and uses the latency-bandwidth pipe