Documentation cleanup

Split make build system documentation out of root README and shake-based build system.

shake/README.mkd

@@ -6,13 +6,6 @@ variety of compile- and run-time metrics. These metrics are recorded in a
 common semi-structured CSV file format, which can be compared and analysed with
 the included `nofib-compare` utility.
 
-## Preparation
-
-The nofib benchmarks require that a number of native dependencies be installed
-in the tested compilers user or global package database. To install these:
-```
-$ cabal v1-install --allow-newer -w /path/to/ghc old-time stm parallel random
-```
 
 ## Usage
 
@@ -21,7 +14,7 @@ By default the results of the run will be placed in `_make/{compiler version}`.
 The compiler version component of this path can be overridden with the
 `--output` flag.
 
-For instance,
+For instance (run from the root `nofib` directory),
 ```
 $ cabal new-run -- nofib-run --compiler=/path/to/ghc --output=test
 ```
@@ -68,7 +61,7 @@ When running with `--cachegrind` tests can be safely parallelised with the
 `-j<n>` flag.
 
 
-### Performance counters
+### Performance counters with `perf_events`
 
 The benchmarks can also be run under the Linux `perf` tool for collection of
 (micro-)architectural event counts. This mode is enabled 
@@ -80,16 +73,6 @@ type in `src/Measurements.hs`) represents semi-structured string keys (known as
 `Label`s) and floating-point values. In particular, labels have a path-like
 structure with `/` being the component delimiter.
 
-An example of this CSV is:
-```
-```
-
-There also exists a JSON representation of this format,
-```
-{
-}
-```
-
 ## Comparing results
 
 ```