Tiny changes to README.md

Update OS X to macOS.

README.md

@@ -14,7 +14,7 @@ _pefile_ is a multi-platform Python module to parse and work with [Portable Exec
 
 The structures defined in the Windows header files will be accessible as attributes in the PE instance. The naming of fields/attributes will try to adhere to the naming scheme in those headers. Only shortcuts added for convenience will depart from that convention.
 
-_pefile_ requires some basic understanding of the layout of a PE file — with it, it's possible to explore nearly every single feature of the PE file format.
+_pefile_ requires some basic understanding of the layout of a PE file — with it, it is possible to explore nearly every single feature of the PE file format.
 
 ### Installation
 
@@ -31,7 +31,7 @@ Some of the tasks that pefile makes possible are:
 * Retrieving embedded data
 * [Reading strings from the resources](https://github.com/erocarrera/pefile/blob/wiki/ReadingResourceStrings.md)
 * Warnings for suspicious and malformed values
-* Basic butchering of PEs, like [writing to some fields](https://github.com/erocarrera/pefile/blob/wiki/UsageExamples.md#reading-and-writing-standard-header-members) and [other parts](https://github.com/erocarrera/pefile/blob/wiki/ModifyingPEImageData.md) of the PE
+* Basic modifying of PEs, like [writing to some fields](https://github.com/erocarrera/pefile/blob/wiki/UsageExamples.md#reading-and-writing-standard-header-members) and [other parts](https://github.com/erocarrera/pefile/blob/wiki/ModifyingPEImageData.md) of the PE
   * This functionality won't rearrange PE file structures to make room for new fields, so use it with care.
   * Overwriting fields should mostly be safe.
 * Packer detection with [PEiD’s signatures](https://github.com/erocarrera/pefile/blob/wiki/PEiDSignatures.md)
@@ -51,7 +51,7 @@ _pefile_ runs in several pipelines scanning hundreds of thousands of new PE file
 
 ## Dependencies
 
-_pefile_ is self-contained. The module has no dependencies; it is endianness independent; and it works on OS X, Windows, and Linux.
+_pefile_ is self-contained. The module has no dependencies; it is endianness independent; and it works on Windows, macOS, and Linux.
 
 ## Recent changes