If I understand correctly though, you’re saying to get around the automatic capitalization of submitted titles by using an overline as the first character? So this title would look like this instead:
‾tvOS for Developers
…but that doesn’t really seem very elegant to me. Perhaps you could achieve a similar affect by using an invisible character at the beginning of the sentence instead, such as U+200B ZERO WIDTH SPACE². Since it’s not in Unicode’s 'Zs' (Separator, space) character category—in addition to its 'Wspace' key having the value 'N'—it’s unlikely that if HN’s code strips leading and trailing whitespace from submitted titles, U+200B ZERO WIDTH SPACE will be stripped.
I guess if that doesn’t work, you could always replace U+0054 LATIN CAPITAL LETTER T with a similar looking lowercase equivalent such as U+0288 LATIN SMALL LETTER T WITH RETROFLEX HOOK³ or even U+1D5CD MATHEMATICAL SANS-SERIF SMALL T⁴ (that’s assuming you’re fine with some people not being able to view it due to not having a font installed with a glyph for that character)… but I’d avoid misusing the semantic significance of those characters like that.
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¹ — https://en.wikipedia.org/wiki/Overline
² — http://graphemica.com/200B