Due to examples and files numerotations and files encoding,
there is a lot of modifications.

* compiler_stages/tc_1/code_to_write.rst,
* compiler_stages/tc_2/chunks.rst,
* compiler_stages/tc_2/error_recovery.rst,
* compiler_stages/tc_2/pretty_printing_samples.rst,
* compiler_stages/tc_3/samples.rst,
* compiler_stages/tc_4/options.rst,
* compiler_stages/tc_4/samples.rst,
* compiler_stages/tc_5/builtin_calls_samples.rst,
* compiler_stages/tc_5/goals.rst,
* compiler_stages/tc_5/optimizing_cascading_if.rst,
* compiler_stages/tc_5/primitive_samples.rst,
* compiler_stages/tc_5/samples_with_variables.rst,
* compiler_stages/tc_6/samples/canonicalization_samples.rst,
* compiler_stages/tc_6/samples/scheduling_samples.rst,
* compiler_stages/tc_7/samples.rst,
* compiler_stages/tc_8/faq.rst,
* compiler_stages/tc_8/samples.rst,
* compiler_stages/tc_9/samples.rst,
* compiler_stages/tc_a/samples.rst,
* compiler_stages/tc_b/samples.rst,
* compiler_stages/tc_d/samples.rst,
* compiler_stages/tc_e/samples.rst,
* compiler_stages/tc_i/samples.rst,
* compiler_stages/tc_l/faq.rst,
* compiler_stages/tc_l/samples.rst,
* compiler_stages/tc_o/samples.rst,
* compiler_stages/tc_r/samples.rst,
* compiler_stages/tc_x/samples.rst,
* compiler_stages/tc_y/faq.rst,
* compiler_stages/tc_y/samples.rst: here.

* compiler_stages/tc_2/hello-world.tig: Add