v1.5.1

Several typos fixed and improved wording in chapter 2

What's Changed

• Review/topic e document after first fgm by @skounis in #380
• Update link to the renamed arf.md by @skounis in #381
• Update README.md by @skounis in #382
• Restore menu item for discussion topics by @skounis in #383
• typos and wrong formats by @paolo-de-rosa in #384
• Topic C - first document by @phin10 in #385
• Topic d to be published 7 feb (#893) by @phin10 in #392
• Release/1.5.1 (#901) by @paolo-de-rosa in #398

Full Changelog: v1.5.0...v1.5.1