Fix links in exporter.md

Fix broken links.

Author: Amanda Butler

docs/reference/contributing/tools/exporter.md

@@ -4,7 +4,7 @@ If you have added a new target to Arm Mbed OS 5, exporting will allow users to t
 
 #### Eclipse and Make
 
-Eclipse project export uses a generated Makefile for building. If `mbed compile -t <toolchain> -m <target>` works, then Mbed `export -i make_<toolchain> -m <target>` will also work. You can find more information about adding and configuring targets [here](/docs/v5.6/reference/arm-mbed-os-porting-guide.html#adding-and-configuring-targets).
+Eclipse project export uses a generated Makefile for building. If `mbed compile -t <toolchain> -m <target>` works, then Mbed `export -i make_<toolchain> -m <target>` will also work. You can find more information about [adding and configuring targets](/docs/v5.6/reference/contributing-target.html).
 
 #### GNU Arm Eclipse managed projects
 
@@ -24,10 +24,10 @@ uVision and IAR both use [CMSIS packs](http://www.keil.com/pack/doc/CMSIS/Pack/h
 
 We use the tool [ArmPackManager](https://github.com/ARMmbed/mbed-os/tree/master/tools/arm_pack_manager) to scrape [MDK5 Software Packs](https://www.keil.com/dd2/Pack/) for target information by parsing [http://www.keil.com/pack/index.idx](http://sadevicepacksprod.blob.core.windows.net/idxfile/index.idx). [index.json](https://github.com/ARMmbed/mbed-os/blob/master/tools/arm_pack_manager/index.json) stores the relevant information in the [PDSC (Pack Description)](http://www.keil.com/pack/doc/CMSIS/Pack/html/) retrieved from each URL in the index.
 
-A `.pdsc` file typically describes a family of devices. Each device is uniquely identified by its [device name](/docs/v5.6/reference/arm-mbed-os-porting-guide.html#adding-and-configuring-targets). This name makes a natural key to associate a device with its information in `index.json`.
+A `.pdsc` file typically describes a family of devices. Each device is uniquely identified by its [device name](/docs/v5.6/reference/contributing-target.html). This name makes a natural key to associate a device with its information in `index.json`.
 
 #### What's in a device name?
-There is no reliable way to map an Mbed alias such as [NUCLEO_F030R8](https://github.com/ARMmbed/mbed-os/blob/master/targets/targets.json#L603) to its unique identifier, [STM32F030R8](https://github.com/ARMmbed/mbed-os/blob/master/targets/targets.json#L615), because it is listed in a CMSIS pack (and subsequently `index.json`). So, we added a [device name](/docs/v5.6/reference/arm-mbed-os-porting-guide.html#adding-and-configuring-targets) field in `targets.json`. **This field is required for IAR or uVision exporter support**.
+There is no reliable way to map an Mbed alias such as [NUCLEO_F030R8](https://github.com/ARMmbed/mbed-os/blob/master/targets/targets.json#L603) to its unique identifier, [STM32F030R8](https://github.com/ARMmbed/mbed-os/blob/master/targets/targets.json#L615), because it is listed in a CMSIS pack (and subsequently `index.json`). So, we added a [device name](/docs/v5.6/reference/contributing-target.html) field in `targets.json`. **This field is required for IAR or uVision exporter support**.
 
 #### Code usage
 [http://www.keil.com/pack/Keil.Kinetis_K20_DFP.pdsc](http://www.keil.com/pack/Keil.Kinetis_K20_DFP.pdsc) is the PDSC that contains TEENSY_31 device (MK20DX256xxx7). ArmPackManager has parsed it, and `index.json` stores it. The device information begins on line 156: