Updated the Installation instructions in the README files of plugins

Author: neelkanth-kaushik

packages/plugins/plugin_adjust/README.md

@@ -8,7 +8,7 @@ Manually add this package to your `pubspec.yaml` file.
 
 ```yaml
 dependencies:
-  analytics_plugin_adjust:
+  segment_analytics_plugin_adjust:
     git:
       url: https://github.com/segmentio/analytics_flutter
       ref: main

packages/plugins/plugin_advertising_id/README.md

@@ -8,7 +8,7 @@ Manually add this package to your `pubspec.yaml` file.
 
 ```yaml
 dependencies:
-  analytics_plugin_advertising_id:
+  segment_analytics_plugin_advertising_id:
     git:
       url: https://github.com/segmentio/analytics_flutter
       ref: main

packages/plugins/plugin_amplitude/README.md

@@ -8,7 +8,7 @@ Manually add this package to your `pubspec.yaml` file.
 
 ```yaml
 dependencies:
-  analytics_plugin_amplitude:
+  segment_analytics_plugin_amplitude:
     git:
       url: https://github.com/segmentio/analytics_flutter
       ref: main

packages/plugins/plugin_appsflyer/README.md

@@ -8,7 +8,7 @@ Manually add this package to your `pubspec.yaml` file.
 
 ```yaml
 dependencies:
-  analytics_plugin_appsflyer:
+  segment_analytics_plugin_appsflyer:
     git:
       url: https://github.com/segmentio/analytics_flutter
       ref: main

packages/plugins/plugin_idfa/README.md

@@ -10,7 +10,7 @@ Manually add this package to your `pubspec.yaml` file.
 
 ```yaml
 dependencies:
-  analytics_plugin_idfa:
+  segment_analytics_plugin_idfa:
     git:
       url: https://github.com/segmentio/analytics_flutter
       ref: main