Add section about inline namespaces

As suggested on issue #15, inline namespaces were missing from the documentation, so I added a sentence with a snippet :)

README.md

@@ -63,6 +63,7 @@ C++11 includes the following new language features:
 - [special member functions for move semantics](#special-member-functions-for-move-semantics)
 - [converting constructors](#converting-constructors)
 - [explicit conversion functions](#explicit-conversion-functions)
+- [inline-namespaces](#inline-namespaces)
 
 C++11 includes the following new library features:
 - [std::move](#stdmove)
@@ -995,6 +996,24 @@ B b{};
 if (b); // OK calls B::operator bool()
 bool bb = b; // error copy-initialization does not consider B::operator bool()
 ```
+### Inline namespaces
+All members of an inline namespace are treated as if they were part of its parent namespace, allowing specialization of functions and easing the process of versioning. This is a transitive property, if A contains B, which in turn contains C and both B and C are inline namespaces, C's members can be used as if they were on A.
+
+```c++
+namespace Program {
+  namespace Version1 {
+    int getVersion() { return 1; }
+    bool isFirstVersion() { return true; }
+  }
+  inline namespace Version2 {
+    int getVersion() { return 2; }
+  }
+}
+
+int version {Program::getVersion()};              // Uses getVersion() from Version2
+int oldVersion {Program::Version1::getVersion()}; // Uses getVersion() from Version1
+bool firstVersion {Program::isFirstVersion()};    // Does not compile when Version2 is added
+```
 
 ## C++11 Library Features