fix: replace Instance Settings with Default Settings in i18n and docs (#8143)

# Which Problems Are Solved

- The console shows the Instance Settings title and a description.
Instance settings should be replaced with Default settings

# How the Problems Are Solved

- The DESCRIPTIONS.SETTINGS.INSTANCE.TITLE and
DESCRIPTIONS.SETTINGS.INSTANCE.DESCRIPTION have been replaced with
Default Settings and in the corresponding translation files.

Here's a screenshot:


![image](https://github.com/zitadel/zitadel/assets/30386061/b404f209-2043-414c-b06d-3291771d54fb)

# Additional Changes

- The docs have been updated to replace remaining texts mentioning
Instance Settings with Default Settings
- Two unused texts have been deleted from the translation files
- VSCode with Prettier have applied some markdown changes

# Additional Context

- Closes #7632

---------

Co-authored-by: Fabi <fabienne@zitadel.com>

console/src/assets/i18n/en.json

@@ -79,8 +79,8 @@
     },
     "SETTINGS": {
       "INSTANCE": {
-        "TITLE": "Instance Settings",
-        "DESCRIPTION": "The instance settings are the default settings for all organizations. With the right permissions, some of them are overridable in organization settings."
+        "TITLE": "Default Settings",
+        "DESCRIPTION": "Default settings for all organizations. With the right permissions, some of them are overridable in organization settings."
       },
       "ORG": {
         "TITLE": "Organization Settings",
@@ -527,7 +527,7 @@
       "TEXT": "All organization settings and tables in console are based on a selected organization. Click this button to switch organization or create a new one."
     },
     "INSTANCE": {
-      "TEXT": "Click here to get to the instance settings. Note that you have only access to this button if you have enhanced permissions."
+      "TEXT": "Click here to get to the default settings. Note that you have only access to this button if you have enhanced permissions."
     },
     "PROFILE": {
       "TEXT": "Here you can switch between your user accounts and manage your sessions and profile."
@@ -1317,10 +1317,6 @@
     }
   },
   "SETTINGS": {
-    "INSTANCE": {
-      "TITLE": "Instance Settings",
-      "DESCRIPTION": "These settings will apply to all your organizations unless they have been overridden."
-    },
     "LIST": {
       "ORGS": "Organizations",
       "FEATURESETTINGS": "Features",