Remove redundant sentences [ci skip]

activestorage/lib/active_storage/analyzer/image_analyzer.rb

@@ -9,8 +9,7 @@ module ActiveStorage
   #   # => { width: 4104, height: 2736 }
   #
   # This analyzer relies on the third-party {MiniMagick}[https://github.com/minimagick/minimagick] gem. MiniMagick requires
-  # the {ImageMagick}[http://www.imagemagick.org] system library. These libraries are not provided by Rails; you must
-  # install them yourself to use this analyzer.
+  # the {ImageMagick}[http://www.imagemagick.org] system library.
   class Analyzer::ImageAnalyzer < Analyzer
     def self.accept?(blob)
       blob.image?

activestorage/lib/active_storage/analyzer/video_analyzer.rb

@@ -16,8 +16,7 @@ module ActiveStorage
   #   ActiveStorage::VideoAnalyzer.new(blob).metadata
   #   # => { width: 640, height: 480, duration: 5.0, angle: 0, aspect_ratio: [4, 3] }
   #
-  # This analyzer requires the {ffmpeg}[https://www.ffmpeg.org] system library, which is not provided by Rails. You must
-  # install ffmpeg yourself to use this analyzer.
+  # This analyzer requires the {ffmpeg}[https://www.ffmpeg.org] system library, which is not provided by Rails.
   class Analyzer::VideoAnalyzer < Analyzer
     def self.accept?(blob)
       blob.video?