After-talk changes

Dependencies

• [2] CBUCBYTV Progress
• [3] 4AZS4L6B Add chapters
• [4] LDVTVP2G All TODOs are gone now
• [5] D7QXCWGA Progress
• [6] NYFLNSVV Add some contents
• [7] 5LKTNB6O LOTS of progress
• [8] 36IPNPIS Handle a few TODOs
• [9] UYGSVBN7 Start the fossil demo
• [*] ARAFRHKU Create the outline of the talk

Change contents

• replacement in sections/4-four-new-kids-on-the-block.md at line 12
  [3.2744706]→[2.51503:51538](∅→∅)
  − ## Four new(er) kinds on the block
  [3.2744706]

  [3.7971659]
  + ## Four new(er) kids on the block
• replacement in sections/6-pijul.md at line 62
  [3.5179]→[2.53914:53954](∅→∅)
  − In contrast, Git doesn't store patches.
  [3.5179]

  [2.53954]
  + In contrast, Git doesn't store any patches.