adding docs and poisson disk benchmark

Author: heckj

ExternalBenchmarks/.benchmarkBaselines/ExternalBenchmarks/bdb4ef08/results.json

@@ -19,11 +19,19 @@ let benchmarks = {
     Benchmark.defaultConfiguration.maxDuration = .seconds(1) // Default = 1 second
     Benchmark.defaultConfiguration.metrics = [.throughput, .wallClock]
 
+    Benchmark("disk2d") { benchmark in
+        var poisson = DiskSampler2D(seed: 0)
+        for _ in benchmark.scaledIterations {
+            blackHole(poisson.generate(radius: 10, width: viewer_size, height: viewer_size))
+        }
+    }
+    
     Benchmark("cell2d") { benchmark in
         for _ in benchmark.scaledIterations {
             blackHole(CellNoise2D(amplitude: 255, frequency: 0.01))
         }
     }
+    
     Benchmark("cell3d") { benchmark in
         for _ in benchmark.scaledIterations {
             blackHole(CellNoise3D(amplitude: 255, frequency: 0.01))

ExternalBenchmarks/Benchmarks/ExternalBenchmarks/ExternalBenchmarks.swift

@@ -8,3 +8,39 @@ in order avoid adding transitive dependencies.
 To run the benchmarks, invoke the following command:
 
     swift package benchmark
+
+## Using Benchmarks
+
+- [Documentation for the package](https://swiftpackageindex.com/ordo-one/package-benchmark/documentation/benchmark/gettingstarted)
+  - [Creating and Comparing Baselines](https://swiftpackageindex.com/ordo-one/package-benchmark/documentation/benchmark/creatingandcomparingbaselines)
+  - [Exporting Benchmark Results](https://swiftpackageindex.com/ordo-one/package-benchmark/documentation/benchmark/exportingbenchmarks)
+
+## Baselines
+
+The baselines are set by commit hash (first 8 hex characters) or (in the future) tag with this work in place.
+The initial baseline is `bdb4ef08`.
+It builds on the tag `1.0.0` with updates to dependencies and Swift versions and no functional code changes.
+
+```bash
+swift package --allow-writing-to-package-directory benchmark baseline update bdb4ef08
+```
+
+To compare current development branch against this baseline, run the following command from this sub-project in the terminal:
+
+```bash
+swift package benchmark baseline compare bdb4ef08
+```
+
+The output defaults to plain text. If you'd like markdown output, for pasting into a pull request, add `--format markdown` to the command.
+
+For a summary comparison, use the command:
+
+```bash
+swift package benchmark baseline check --check-absolute
+```
+
+### Stored Baselines
+
+`bdb4ef08`: M1 macbook pro, 16GB ram, running only iTerm2
+
+