doc: move porting guide into doc/ and add to index

This moves all the documentation under the doc/ tree for consistency.

Replace the link to include/spdk/env.h to raw text - the Doxygen
Markdown parser will automatically turn it into a link since it is a
Doxygen input file.

Change-Id: If6bde1cfc965cada2c741acd5505026545ad4cf7
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>

CHANGELOG.md

@@ -73,7 +73,7 @@ by the NVMe library.
 The `env` environment abstraction library has been introduced, and a default
 DPDK-based implementation is provided as part of SPDK.  The goal of the `env`
 layer is to enable use of alternate user-mode memory allocation and PCI access
-libraries.  See `PORTING.md` for more details.
+libraries.  See `doc/porting.md` for more details.
 
 The build process has been modified to produce all of the library files in the
 `build/lib` directory.  This is intended to simplify the use of SPDK from external

README.md

@@ -24,7 +24,7 @@ Documentation
 =============
 
 [Doxygen API documentation](http://www.spdk.io/doc/) is available, as
-well as a [Porting Guide](PORTING.md) for porting SPDK to different frameworks
+well as a [Porting Guide](http://www.spdk.io/doc/porting.html) for porting SPDK to different frameworks
 and operating systems.
 
 Many examples are available in the `examples` directory.

doc/Doxyfile

@@ -761,6 +761,7 @@ WARN_LOGFILE           =
 INPUT                  = ../include/spdk \
                          index.md \
                          directory_structure.md \
+                         porting.md \
                          ioat/index.md \
                          nvme/index.md \
                          nvme/async_completion.md \

doc/index.md

@@ -14,6 +14,7 @@ which avoids kernel context switches and eliminates interrupt handling overhead.
 ## General Information {#general}
 
  - @ref directory_structure
+ - @ref porting
 
 ## Modules {#modules}
 

doc/porting.md

@@ -1,12 +1,11 @@
-SPDK Porting Guide
-==================
+# SPDK Porting Guide {#porting}
 
 SPDK is ported to new environments by implementing the *env*
 library interface.  The *env* interface provides APIs for drivers
 to allocate physically contiguous and pinned memory, perform PCI
 operations (config cycles and mapping BARs), virtual to physical
 address translation and managing memory pools.  The *env* API is
-defined in [include/spdk/env.h](include/spdk/env.h).
+defined in include/spdk/env.h.
 
 SPDK includes a default implementation of the *env* library based
 on the Data Plane Development Kit ([DPDK](http://dpdk.org/)).