Improve javadoc for some addons (#15701)

Signed-off-by: Holger Friedrich <mail@holger-friedrich.de>

bundles/org.openhab.binding.avmfritz/src/main/java/org/openhab/binding/avmfritz/internal/dto/DeviceListModel.java

@@ -29,6 +29,7 @@ import javax.xml.bind.annotation.XmlType;
  * devicelist version 1 (currently used by AVM) response:
  *
  * <pre>
+ * {@code
  * <devicelist version="1">
  * <device identifier="##############" id="##" functionbitmask="2944" fwversion="03.83" manufacturer="AVM" productname=
  * "FRITZ!DECT 200">
@@ -73,8 +74,8 @@ import javax.xml.bind.annotation.XmlType;
  * </hkr>
  * </device>
  * </devicelist>
- *
- * <pre>
+ * }
+ * </pre>
  *
  * @author Robert Bausdorf - Initial contribution
  * @author Christoph Weitkamp - Added support for groups

bundles/org.openhab.binding.avmfritz/src/main/java/org/openhab/binding/avmfritz/internal/dto/HeatingModel.java

@@ -222,8 +222,8 @@ public class HeatingModel implements BatteryModel {
 
     /**
      * Converts a celsius value to a FRITZ!Box value.
-     * Valid celsius values: 8 to 28 °C > 16 to 56
-     * 16 <= 8°C, 17 = 8.5°C...... 56 >= 28°C, 254 = ON, 253 = OFF
+     * Valid celsius values: 8 to 28 °C > 16 to 56,
+     * 16 &lt;= 8°C, 17 = 8.5°C...... 56 >= 28°C, 254 = ON, 253 = OFF
      *
      * @param celsiusValue The celsius value to be converted
      * @return The FRITZ!Box value

bundles/org.openhab.binding.avmfritz/src/main/java/org/openhab/binding/avmfritz/internal/hardware/FritzAhaWebInterface.java

@@ -220,7 +220,7 @@ public class FritzAhaWebInterface {
      * Constructs an URL from the stored information, a specified path and a specified argument string
      *
      * @param path Path to include in URL
-     * @param args String of arguments, in standard HTTP format (arg1=value1&arg2=value2&...)
+     * @param args String of arguments, in standard HTTP format ({@code arg1=value1&arg2=value2&...})
      * @return URL
      */
     public String getURL(String path, String args) {