Added comments to Java demos.

demo/java/src/main/java/io/github/cosinekitty/astronomy/demo/MoonPhase.java

@@ -2,6 +2,13 @@ package io.github.cosinekitty.astronomy.demo;
 import io.github.cosinekitty.astronomy.*;
 
 public class MoonPhase {
+    /**
+     * Display Moon phase information and the next 10 quarter phases.
+     *
+     * @param time
+     * The date and time for which to display Moon phase information,
+     * and when to initiate a search for the subsequent quarter phases.
+     */
     public static int run(Time time) {
         // Calculate the Moon's ecliptic phase angle,
         // which ranges from 0 to 360 degrees.

demo/java/src/main/java/io/github/cosinekitty/astronomy/demo/Positions.java

@@ -8,7 +8,7 @@ public class Positions {
     };
 
     /**
-     * Display equatorial and horizontal coordinates of solar system bodies.
+     * Print a table of solar system body positions in equatorial and horizontal coordinates.
      *
      * @param observer
      * The geographic location for which to calculate positions.

demo/java/src/main/java/io/github/cosinekitty/astronomy/demo/Seasons.java

@@ -2,6 +2,12 @@ package io.github.cosinekitty.astronomy.demo;
 import io.github.cosinekitty.astronomy.*;
 
 public class Seasons {
+    /**
+     * Print the times of the equinoxes and solstices for a calendar year.
+     *
+     * @param year
+     * The calendar year value for which to find equinoxes and solstices.
+     */
     public static int run(int year) {
         SeasonsInfo seasons = Astronomy.seasons(year);
         System.out.printf("March equinox     : %s%n", seasons.getMarchEquinox());