fix: correct typo and grammar in Dock Block help string (#6673)

- 'The Dock block block connections two blocks.' → 'The Dock block connects two blocks.'
- Updated translation key in locales/en.json and all locale JSON files
- Updated msgid in po/MusicBlocks.pot and all .po files

Closes #6672

Co-authored-by: gourijain026@gmail.com <gourijain@example.com>

Author: gourijain029-del

js/blocks/ProgramBlocks.js

@@ -1011,11 +1011,7 @@ function setupProgramBlocks(activity) {
         constructor() {
             super("dockblock");
             this.setPalette("program", activity);
-            this.setHelpString([
-                _("The Dock block block connections two blocks."),
-                "documentation",
-                ""
-            ]);
+            this.setHelpString([_("The Dock block connects two blocks."), "documentation", ""]);
 
             this.formBlock({
                 /**