Adding Runtime.md documenting GamesRunnr and FPSAnalyzr (#21)

Runtime.md

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+This guide will describe how GamesRunnr runs upkeep functions and how FSPAnalyzer is used to schedule them in GameStartr projects.
+
+### Table of Contents
+1. [GamesRunnr](#gamesrunnr)
+    1. [Upkeep](#games-and-upkeep)
+    2. [Interval and Speed](#interval-and-speed)
+    3. [Pause and Play](#pause-and-play)
+2. [FPSAnalyzer](#fpsanalyzer)
+    1. [Measure](#measure)
+    2. [Getters](#getters)
+
+# GamesRunnr
+
+GamesRunnr is a module for running a series of callbacks grouped into one interval.
+These callbacks deal with maintaining the state of the game, like having a callback to redraw the canvas.
+These callbacks separately are referred to as games.
+
+## Upkeep
+
+`upkeep` is a function that runs each game once.
+`upkeepTimed` is a utility function for `upkeep` that times and returns the amount of time it takes to run all the games.
+
+```typescript
+let totalTime: number = GamesRunner.upkeepTimed();
+console.log(`It took `${totalTime}` ms.`);
+```
+
+## Interval and Speed
+
+Each call of `upkeep` has a set time delay, in milliseconds, before it can be called again, called an interval.
+To set the interval use `setInterval`.
+
+```typescript
+GamesRunner.setInterval(20);
+```
+
+`speed` is a variable which represents the playback speed of the intervals, for example a speed of 2 makes the intervals go by twice as fast.
+To set the value, use `setSpeed`.
+
+```typescript
+GamesRunner.setSpeed(2);
+```
+
+## Pause and Play
+
+GamesRunnr can pause and continue `upkeep` execution.
+`pause` stops the execution of `upkeep` and cancels the next call of upkeep.
+
+```typescript
+GamesRunner.pause();
+```
+
+`play` continues execution of `upkeep` by calling it.
+
+```typescript
+GamesRunner.play();
+```
+
+Both `pause` and `play` allow for trigger functions to run when they are called by defining `onPause` and `onPlay`.
+
+```typescript
+let GamesRunner: IGamesRunnr = new GamesRunnr({
+    games: [() => console.log("example function")],
+    onPause: () => console.log("upkeep is paused"),
+    onPlay: () => console.log("upkeep is resumed")
+});
+GamesRunner.pause();
+GamesRunner.play();
+```
+
+To toggle between the two, use `togglePause`.
+
+```typescript
+GamesRunner.togglePause();
+```
+
+More can be read on GamesRunnr on its [Readme](https://github.com/FullScreenShenanigans/GamesRunnr/blob/master/README.md).
+
+# FPSAnalyzr
+
+## Measure
+
+FSPAnalyzr is a module for recording and analyzing framerate measurements.
+
+`measure` and is run at the end of every `upkeep` call.
+
+```typescript
+FPSAnalyzer.measure();
+```
+
+It updates the value for the current timestamp and if there was a previous timestamp recorded, it adds an FPS measurement to the list of recorded measurements with `addFPS`.
+
+```typescript
+FPSAnalyzer.addFPS(40);
+```
+
+## Getters
+
+FPSAnalyzer has a number of getter functions that return statistics and information on the recorded measurements.
+
+```typescript
+FSPAnalyzer.getNumRecorded();
+FSPAnalyzer.getTicker();
+FPSAnalyzer.getMeasurements();
+FPSAnalyzer.getDifferences();
+FPSAnalyzer.getAverage();
+FPSAnalyzer.getMedian();
+FPSAnalyzer.getExtremes();
+FPSAnalyzer.getRange();
+```
+
+More can be read on FPSAnalyzr on its [Readme](https://github.com/FullScreenShenanigans/FPSAnalyzr/blob/master/README.md).