Add link to C2MIR blogpost.
To recognize compilation by C-to-MIR compiler, compiler specific
macros `__mirc__` and `__MIRC__` defined as 1 can be used.
+ An additional information about C-to-MIR compiler can be found in
+ [this blog post](https://developers.redhat.com/blog/2021/04/27/the-mir-c-interpreter-and-just-in-time-jit-compiler)
+
## C to MIR compiler as usual C compiler
The project makefile builds program `c2m` which can compile C and
MIR files given on the command line and produce MIR code or execute
