README.txt: Documentation and license to distribute with prebuilt toolchain

Author: sboucherjis

README.txt

@@ -0,0 +1,23 @@
+This software distribution includes builds of:
+ - GCC 14.2.0, available from https://gcc.gnu.org
+ - GNU Binutils 2.43.1, available from https://sourceware.org/binutils
+ - GMP 6.3.0, available from https://gmplib.org
+ - MPFR 4.2.1, available from https://www.mpfr.org
+ - MPC 1.3.1, available from https://www.multiprecision.org
+
+All are free software. You can redistribute and/or modify GCC and Binutils
+under the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later version.
+You can redistribute and/or modify GMP, MPFR, and MPC under the terms of the
+GNU Lesser General Public License as published by the Free Software Foundation;
+either version 3 of the License, or (at your option) any later version.
+
+To see the full build configuration, issue the command:
+ $ riscv32-gcc -v
+
+For full documentation, issue one of the following commands:
+ - info as
+ - info binutils
+ - info ld
+ - info cpp
+ - info gcc