Add documentation for unit package

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/AreaUnit.kt

@@ -17,6 +17,9 @@ public interface AreaUnit {
      */
     public val symbol: String
 
+    /**
+     * A non-standard representation of area commonly used as part of the metric system.
+     */
     public enum class Metric(override val symbol: String, override val millimetersSquaredScale: Long) : AreaUnit {
         Decimilliare("dma", 100),
         Centiare("ca", 1_000_000),

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/EnergyUnit.kt

@@ -16,6 +16,9 @@ public interface EnergyUnit {
      */
     public val symbol: String
 
+    /**
+     * An International System of Units standard representation of energy.
+     */
     public enum class International(
         override val millijouleScale: Long,
         override val symbol: String,
@@ -29,6 +32,9 @@ public interface EnergyUnit {
         Petajoule(1_000_000_000_000_000_000, "PJ"),
     }
 
+    /**
+     * A non-standard representation of energy commonly used to measure electrical energy.
+     */
     public enum class Electricity(
         override val millijouleScale: Long,
         override val symbol: String,

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/ForceUnit.kt

@@ -1,11 +1,24 @@
 package io.github.kevincianfarini.alchemist.unit
 
+/**
+ * A unit of force precise to the nanonewton.
+ */
 public interface ForceUnit {
 
+    /**
+     * The symbol of this unit.
+     */
     public val symbol: String
 
+    /**
+     * The amount of nanonewtons in this unit. Implementations of [ForceUnit] should be perfectly divisible by a
+     * quantity of nanonewtons.
+     */
     public val nanonewtonScale: Long
 
+    /**
+     * An International System of Units standard representation of force.
+     */
     public enum class International(override val symbol: String, override val nanonewtonScale: Long) : ForceUnit {
         Nanonewton("nN", 1),
         Micronewton("μN", 1_000),

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/LengthUnit.kt

@@ -16,6 +16,9 @@ public interface LengthUnit {
      */
     public val symbol: String
 
+    /**
+     * An International System of Units standard representation of length.
+     */
     public enum class International(
         override val nanometerScale: Long,
         override val symbol: String,
@@ -30,6 +33,9 @@ public interface LengthUnit {
         Gigameter(1_000_000_000_000_000_000, "Gm"),
     }
 
+    /**
+     * A non-standard representation of length commonly used in the United States.
+     */
     public enum class UnitedStatesCustomary(
         override val nanometerScale: Long,
         override val symbol: String,

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/MassUnit.kt

@@ -1,11 +1,24 @@
 package io.github.kevincianfarini.alchemist.unit
 
+/**
+ * A unit of mass precise to the microgram.
+ */
 public interface MassUnit {
 
+    /**
+     * The amount of micrograms in this unit. Implementations of [MassUnit] should be perfectly divisible by a
+     * quantity of micrograms.
+     */
     public val microgramScale: Long
 
+    /**
+     * The symbol of this unit.
+     */
     public val symbol: String
 
+    /**
+     * An International System of Units standard representation of mass.
+     */
     public enum class International(override val microgramScale: Long, override val symbol: String): MassUnit {
         Microgram(1, "μg"),
         Milligram(1_000, "mg"),

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/PowerUnit.kt

@@ -16,6 +16,9 @@ public interface PowerUnit {
      */
     public val symbol: String
 
+    /**
+     * An International System of Units standard representation of power.
+     */
     public enum class International(
         override val microwattScale: Long,
         override val symbol: String,

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/TemperatureUnit.kt

@@ -5,6 +5,9 @@ import io.github.kevincianfarini.alchemist.internal.saturated
 import kotlin.math.roundToLong
 import kotlin.text.Typography.nbsp
 
+/**
+ * Marks [TemperatureUnit] as delicate for implementation.
+ */
 @RequiresOptIn(
     message = """
         Implementing TemperatureUnit requires detecting integer overflow detection, which normal Long values don't 
@@ -42,6 +45,9 @@ public interface TemperatureUnit {
      */
     public fun convertNanokelvinsToThis(nanokelvins: Long): Double
 
+    /**
+     * An International System of Units standard representation of temperature.
+     */
     public enum class International(override val symbol: String) : TemperatureUnit {
         Nanokelvin("${nbsp}nK") {
             override fun convertToNanokelvin(degrees: Long): Long = degrees
@@ -120,6 +126,9 @@ public interface TemperatureUnit {
         },
     }
 
+    /**
+     * A non-standard unit of temperature used in the United States.
+     */
     public object Fahrenheit : TemperatureUnit {
         override val symbol: String get() = "°F"
         override fun convertToNanokelvin(degrees: Long): Long {

src/commonMain/kotlin/io/github/kevincianfarini/alchemist/unit/VolumeUnit.kt

@@ -2,12 +2,25 @@ package io.github.kevincianfarini.alchemist.unit
 
 import kotlin.text.Typography.nbsp
 
+/**
+ * A unit of volume precise to the centimeter³.
+ */
 public interface VolumeUnit {
 
+    /**
+     * The symbol of this unit.
+     */
     public val symbol: String
 
+    /**
+     * The amount of centimeter³ in this unit. Implementations of [TemperatureUnit] should be perfectly divisible by a
+     * quantity of centimeter³.
+     */
     public val cubicCentimetersScale: Long
 
+    /**
+     * A non-standard representation of volume commonly used as part of the metric system.
+     */
     public enum class Metric(override val symbol: String, override val cubicCentimetersScale: Long) : VolumeUnit {
         Milliliter("${nbsp}mL", 1),
         Liter("${nbsp}L", 1_000),