Definitely wrong sub-forum, this one is for Playtest of future version (with very different mechanics), so expect this thread to be moved to correct sub-forum. No worries though, this can happen even by mistake if you have multiple tabs open etc.
As Edge93 said, SoS is archetype for original Monk class, and is not technically compatible with Unchained Monk because Unchained Monk does not have High Jump and Abundant Step class abilities. Unchained Monk having Ki Powers allowing to achieve same things technically still does not qualify, even ignoring the different level requirement for those abilities than Original Monk grants them at. SoS archetype's replacement abilities also are granted at different levels than ability they are replacing which makes direct translation to Unchained doubly problematic, never mind that comparing Bones of Stone with Unchained's own Diamond Resiience DR ability shows latter makes former obsolete, reflecting the very different assumptions of SoS archetype vs Unchained.
It's really simplest to just use original Monk chassis if you want to use SoS archetype, and you can also use Qi Gong archetype with it to get flexibility of Ki Powers to repace any abilities that SoS doesn't replace OR alter. Understand that Unchained Monk is basically a power upgrade to original Monk without archetypes (albeit shifting direction somewhat, away from all Good Saves, to Full BAB) but in comparison to stronger archetypes for original Monk it is probably largely equivalent in power... Which has the corrollary that simply applying original Monk archetypes to Unchained Monk (assuming ability swap problems don't exist or are accomodated for) can easily be over-powered generally speaking (albeit Bones of Stone in particular clearly isn't).
FYI, d20pfsrd has no official standing, so treating what they do or don't republish as meaningful is not advised, it's really up to their specific situation and arbitrary choices. In fact they do republish SoS, simply under their page for Oread race: http://www.d20pfsrd.com/races/other-races/featured-races/arg-oread
d20pfsrd's approach liberally reorganizes much of the material they publish, divorcing specific material from it's specific source book context (although they mostly indicate that in sub-scripts, that context is still functionally alienated from material). That they republish SoS under Oread page but don't link it within Monk page is actually divergence from their norm, but again, not ultimately meaningful regardless of their internal consistency.
A more officially supported (albeit still independent) source is Archives of Nethys (aonprd.com), which includes more Golarion-specific material which d20pfsrd cannot republish (due to ad monetization conflict with Paizo licence). Archives of Nethys actually now ALSO hosts what was Paizo's own official Pathfinder Reference Document (at legacy.aonprd.com) which 100% clearly respects original book source structure (the main Nethys page has similar de-constructive approach to content as d20pfsrd, albeit distinct in details and UI etc)
Pathfinderwiki.com is another community source gathering open source material giving context to what meaning things like Oread actually have in a setting context, distinct from mechanics.
