Fix "in memory" where it should be "in-memory".

activesupport/lib/active_support/cache/file_store.rb

@@ -8,7 +8,7 @@ module ActiveSupport
     # A cache store implementation which stores everything on the filesystem.
     #
     # FileStore implements the Strategy::LocalCache strategy which implements
-    # an in memory cache inside of a block.
+    # an in-memory cache inside of a block.
     class FileStore < Store
       attr_reader :cache_path
 

activesupport/lib/active_support/cache/mem_cache_store.rb

@@ -21,7 +21,7 @@ module ActiveSupport
     #   server goes down, then MemCacheStore will ignore it until it comes back up.
     #
     # MemCacheStore implements the Strategy::LocalCache strategy which implements
-    # an in memory cache inside of a block.
+    # an in-memory cache inside of a block.
     class MemCacheStore < Store
       module Response # :nodoc:
         STORED      = "STORED\r\n"

activesupport/lib/active_support/cache/strategy/local_cache.rb

@@ -4,9 +4,9 @@ require 'active_support/core_ext/string/inflections'
 module ActiveSupport
   module Cache
     module Strategy
-      # Caches that implement LocalCache will be backed by an in memory cache for the
+      # Caches that implement LocalCache will be backed by an in-memory cache for the
       # duration of a block. Repeated calls to the cache for the same key will hit the
-      # in memory cache for faster access.
+      # in-memory cache for faster access.
       module LocalCache
         # Simple memory backed cache. This cache is not thread safe and is intended only
         # for serving as a temporary memory cache for a single thread.