fixed typos

Author: Xandkeeper

src/preface.md

@@ -117,12 +117,13 @@ $ sudo apt-get install qemu-system-arm
 
 ## Installing a toolchain bundle from ARM (optional step) (tested on Ubuntu 18.04)
 - With the late 2018 switch from
-[GCC's linker to LLB](https://rust-embedded.github.io/blog/2018-08-2x-psa-cortex-m-breakage/) for Cortex-M microcontrollers, [gcc-arm-none-eabi][1] is no longer 
+[GCC's linker to LLD](https://rust-embedded.github.io/blog/2018-08-2x-psa-cortex-m-breakage/) for Cortex-M 
+microcontrollers, [gcc-arm-none-eabi][1] is no longer 
 required.  But for those wishing to use the toolchain 
 anyway, install from [here][1] and follow the steps outlined below:
 ``` console
 $ tar xvjf gcc-arm-none-eabi-8-2018-q4-major-linux.tar.bz2
 $ mv gcc-arm-none-eabi-<version_downloaded> <your_desired_path> # optional
 $ export PATH=${PATH}:<path_to_arm_none_eabi_folder>/bin # add this line to .bashrc to make persistent
-[1]: https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads
 ```
+[1]: https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads