Fix any wrong in messages

Author: aycabta

readline.gemspec

@@ -6,8 +6,8 @@ Gem::Specification.new do |spec|
 
   spec.summary       = %q{It's a loader for "readline".}
   spec.description   = <<~EOD
-    This is just loader for "readline". If Ruby has "readline-ext" gem that
-    is a native extension, this gem will load its first. If Ruby doesn't have
+    This is just a loader for "readline". If Ruby has "readline-ext" gem that
+    is a native extension, this gem will load it first. If Ruby doesn't have
     the "readline-ext" gem this gem will load "reline" that is a compatible
     library with "readline-ext" gem and is implemented by pure Ruby.
   EOD
@@ -18,8 +18,8 @@ Gem::Specification.new do |spec|
   spec.require_paths = ['lib']
 
   spec.post_install_message = <<~EOM
-    This is just loader for "readline". If Ruby has "readline-ext" gem that
-    is a native extension, this gem will load its first. If Ruby doesn't have
+    This is just a loader for "readline". If Ruby has "readline-ext" gem that
+    is a native extension, this gem will load it first. If Ruby doesn't have
     the "readline-ext" gem this gem will load "reline" that is a compatible
     library with "readline-ext" gem and is implemented by pure Ruby.