Fixed inconsistencies (#9120)

* Fixed inconsistencies

See https://pre-release.mattermost.com/core/pl/339m9zipst8n7kc19fossntose

* Update en.json

i18n/en.json

@@ -381,7 +381,7 @@
   },
   {
     "id": "api.command_channel_header.permission.app_error",
-    "translation": "You do not have the appropriate permissions to edit the channel header."
+    "translation": "You don't have the appropriate permissions to edit the channel header."
   },
   {
     "id": "api.command_channel_header.update_channel.app_error",
@@ -413,7 +413,7 @@
   },
   {
     "id": "api.command_channel_purpose.permission.app_error",
-    "translation": "You do not have the appropriate permissions to edit the channel purpose."
+    "translation": "You don't have the appropriate permissions to edit the channel purpose."
   },
   {
     "id": "api.command_channel_purpose.update_channel.app_error",
@@ -445,7 +445,7 @@
   },
   {
     "id": "api.command_channel_rename.permission.app_error",
-    "translation": "You do not have the appropriate permissions to rename the channel."
+    "translation": "You don't have the appropriate permissions to rename the channel."
   },
   {
     "id": "api.command_channel_rename.too_long.app_error",
@@ -840,7 +840,7 @@
   },
   {
     "id": "api.command_remove.permission.app_error",
-    "translation": "You do not have the appropriate permissions to remove the member."
+    "translation": "You don't have the appropriate permissions to remove the member."
   },
   {
     "id": "api.command_remove.user_not_in_channel",