Add clarity for the large pool of buffers and the GetBuffer method pe…

…rtaining to the .NET max array length (#370)

README.md

@@ -63,7 +63,7 @@ Read the change log [here](https://github.com/microsoft/Microsoft.IO.RecyclableM
 The `RecyclableMemoryStreamManager` class maintains two separate pools of objects:
 
 1. **Small Pool** - Holds small buffers (of configurable size). Used by default for all normal read/write operations. Multiple small buffers are chained together in the `RecyclableMemoryStream` class and abstracted into a single stream.
-2. **Large Pool** - Holds large buffers, which are only used when you must have a single, contiguous buffer, such as when you plan to call `GetBuffer()`. It is possible to create streams larger than is possible to be represented by a single buffer because of .NET's array size limits.
+2. **Large Pool** - Holds large buffers, which are only used when you must have a single, contiguous buffer, such as when you plan to call `GetBuffer()`. The `GetBuffer()` method is still bounded by .NET array size limits. If you need a larger stream than this, do not use this method.
 
 A `RecyclableMemoryStream` starts out by using a small buffer, chaining additional ones as the stream capacity grows. Should you ever call `GetBuffer()` and the length is greater than a single small buffer's capacity, then the small buffers are converted to a single large buffer. You can also request a stream with an initial capacity; if that capacity is larger than the small pool block size, multiple blocks will be chained unless you call an overload with `asContiguousBuffer` set to true, in which case a single large buffer will be assigned from the start. If you request a capacity larger than the maximum poolable size, you will still get a stream back, but the buffers will not be pooled. (Note: This is not referring to the maximum array size. You can limit the poolable buffer sizes in `RecyclableMemoryStreamManager`)