translation of comments and some other german terms

assets/i18n.json

@@ -1,7 +1,7 @@
 {
   "en": {
     "pageTitle": "Jitsi Meeting",
-    "impressum": "Legal Notice",
+    "legal_notice": "Legal Notice",
     "source": "Source",
     "launcher": {
       "title": "Jitsi Meeting",
@@ -91,7 +91,7 @@
   },
   "de": {
     "pageTitle": "Jitsi Meeting öffnen",
-    "impressum": "Impressum",
+    "legal_notice": "Impressum",
     "source": "Quellcode",
     "launcher": {
       "title": "Jitsi Meeting",
@@ -181,7 +181,7 @@
   },
   "fr": {
     "pageTitle": "Réunion Jitsi",
-    "impressum": "Mentions légales",
+    "legal_notice": "Mentions légales",
     "source": "Code source",
     "launcher": {
       "title": "Réunion Jitsi",
@@ -271,7 +271,7 @@
   },
   "zh": {
     "pageTitle": "Jitsi 会议",
-    "impressum": "法律声明",
+    "legal_notice": "法律声明",
     "source": "源代码",
     "launcher": {
       "title": "Jitsi 会议",