assignments: fix pthl submission date, given code part, broken links

* ../compiler_stages/pthl/pthl.rst,
* source/compiler_stages/tc_1/tc_1.rst,
* source/compiler_stages/tc_2/tc_2.rst,
* given_code.rst: here.
1 job for master in 23 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #31050
trigger-tc

00:00:23