The line breaks don't show up properly on github because the file extension (.md) triggers the rendered view, which ignores single line breaks in the code. The result is a string of copyright notices in a single long line, without a clear separation between entries. One solution is as done here, to use a single "Copyright (c)" and split the authors list by adding commas. An alternative would be to format the notice as a bulleted list. Another is adding explicit line breaks to the source code (but that would make it less readable in plain text mode). Finally, one could simply add commas to the end of each line, but the repeated "Copyright (c)" would be redundant, since a single copyright notice can have multiple authors.
As for the license title, it's not a strict legal requirement, but it's included in pretty much every template of this license as published by SPDX, OSI, Wikipedia, and others.
add license title; format authors list for display
Fix LICENSE.md formatting issue.
Added trailing double-spaces to indicate single line breaks.
The license is an older version of the ISC License without the controversial 'and/or'. The older version did not have 'ISC License' at the top. I am concerned that adding 'ISC License' could be misconstrued to imply that the latest version of the ISC License should apply. For now I kept LICENSE.md like spectrwm.c and fixed the line break issue by adding double spaces at the end of the lines.
@LordReg understood, thanks for the clarification.