Renames files /doc/training-guides/common/

Renames files with tags 'modulexxx' and 'chxxx'
with cleaner tags 'section'.

Partial-bug: 1338684

Change-Id: I55496cbd645d3538cad1bbac1e0f73d94f02f75b
Merge "Renames files /doc/training-guides/common/"