Fix some messages

Addresses BUKKIT-5272, BUKKIT-5282, and BUKKIT-5283

By: Wesley Wolfe <weswolf@aol.com>

paper-api/src/main/java/org/bukkit/command/defaults/SayCommand.java

@@ -14,7 +14,7 @@ import com.google.common.collect.ImmutableList;
 public class SayCommand extends VanillaCommand {
     public SayCommand() {
         super("say");
-        this.description = "Broadcasts the given message as the console";
+        this.description = "Broadcasts the given message as the sender";
         this.usageMessage = "/say <message ...>";
         this.setPermission("bukkit.command.say");
     }

paper-api/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java

@@ -95,7 +95,7 @@ final class PluginClassLoader extends URLClassLoader {
         Validate.notNull(javaPlugin, "Initializing plugin cannot be null");
         Validate.isTrue(javaPlugin.getClass().getClassLoader() == this, "Cannot initialize plugin outside of this class loader");
         if (this.plugin != null || this.pluginInit != null) {
-            throw new IllegalArgumentException("Plugin already intialized!", pluginState);
+            throw new IllegalArgumentException("Plugin already initialized!", pluginState);
         }
 
         pluginState = new IllegalStateException("Initial initialization");

paper-api/src/main/java/org/bukkit/plugin/messaging/ChannelNotRegisteredException.java

@@ -10,6 +10,6 @@ public class ChannelNotRegisteredException extends RuntimeException {
     }
 
     public ChannelNotRegisteredException(String channel) {
-        super("Attempted to send a plugin message through an unregistered channel ('" + channel + "'.");
+        super("Attempted to send a plugin message through the unregistered channel `" + channel + "'.");
     }
 }