Revert "add no6897XsM.md and (part of) its subcategories"

This reverts commit 996208fce27d9ec6c32621f2dd5cbe7552b389b3.
Revert "fix url links"

This reverts commit 39de2b152b32eb898aaca10c1999d9a1a459bf0d.
Revert "add noFGleS3sa.md, no_adcwNt_.md, no2480eqy.md, no2114NIs.md and their subcategories"

This reverts commit 5d45377f5874b0af60209822681a4cadc9af6207.
Revert "fix for <pre><code> tags"

This reverts commit ee75909ba882060e4f4f2224fc1d75c5bd360cc7.
fix for rendering test (temoral commit)