Ambiguous for-less link for 'grapheme cluster' about webauthn

[emlun]

2023-03-08 call: Probably use the i18n-glossary definition if it seems applicable enough. @emlun to compare and open a PR.

[emlun]

I'm not sure how I identified http://www.unicode.org/versions/latest/ch02.pdf as the primary further reference from i18n-glossary. At the moment, the definition reads:

Grapheme cluster. A grapheme cluster is defined by the Unicode Standard as the default mechanism for computing an approximation to graphemes (see Unicode Standard Annex #29: Text Segmentation [UAX29]). Two types of default grapheme cluster are defined. Unless otherwise noted, grapheme cluster in this document refers to an extended default grapheme cluster. (A discussion of grapheme clusters is also given in Section 2 of the Unicode Standard, [Unicode]. Cf. near the end of Section 2.11 in version 14.0 of The Unicode Standard.) Because different natural languages have different needs, grapheme clusters can also sometimes require tailoring. For example, a Slovak user might wish to treat the default pair of grapheme clusters "ch" as a single grapheme cluster. Note that the interaction between the language of string content and the end-user's preferences might be complex.

The first parenthetical links to https://www.unicode.org/reports/tr29/tr29-39.html which is an earlier revision (39) of our current link, https://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries (currently revision 41). The contents of the "Grapheme Cluster Boundaries" section looks identical between these two revisions.

Given this I judge that we can safely drop our anchor for [=grapheme cluster=] and use the definition from i18n-glossary instead.