README: Update installation instructions

INSTALL.md

@@ -6,20 +6,25 @@ This document describes how to install tools required by CM-Makefile.
 
 ### GCC ARM Embedded Toolchain
 
-The toolchain can be installed from PPA:
+The toolchain can be installed from repositories (unfortunately, the Ubuntu
+repository does not contain GDB):
 
-	sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa
-	suto apt-get update
 	sudo apt-get install gcc-arm-embedded
 
-It is also possible to download a specific version of the toolchain directly
-from the [website][1]. In this case, it might be necessary to obtain 32-bit
-`libc` and `libncurses` (required by `gdb`):
+A preferred way is to install the latest toolchain (with GDB which is needed for
+debugging or for flashing with the Black Magic Probe) downloaded directly from
+[Arm website][1]. In this case, it might be necessary to obtain 32-bit `libc`
+and `libncurses` (required by GDB):
 
 	sudo apt-get install libc6:i386 libncurses5:i386
 
-To use a specific toolchain version, set the `CROSS_COMPILE` variable
-accordingly, e.g.:
+Then simply add the toolchain to `PATH`:
+
+	echo "export PATH="/path/to/gcc-arm-none-eabi-8-2018-q4-major/bin:$PATH"" >> ~/.bashrc
+	source ~/.bashrc
+
+Alternatively (or to use a specific toolchain version), set the `CROSS_COMPILE`
+variable when running `make`:
 
 	make CROSS_COMPILE=/usr/local/gcc-arm-none-eabi-4_9-2015q3/bin/arm-none-eabi-
 
@@ -29,4 +34,7 @@ OpenOCD can be installed from Ubuntu repository:
 
 	sudo apt-get install openocd
 
-[1]: https://launchpad.net/gcc-arm-embedded
+However, as the release cycle is rather slow, it might be more useful to compile
+it from sources (especially when working with newer MCUs).
+
+[1]: https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads

README.md

@@ -113,7 +113,7 @@ version.
 
 See `COPYING` and `COPYING.LESSER` for details.
 
-[1]: https://launchpad.net/gcc-arm-embedded
+[1]: https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm
 [2]: http://openocd.org/
 [3]: https://wiki.eclipse.org/CDT/StandaloneDebugger
 [4]: https://github.com/ntfreak/openocd/tree/master/tcl/board