Issue #2810621 by Gábor Hojtsy, dawehner, xjm, jhodgdon, klausi, Wim Leers: Improve core.api.php documentation about browsertests and javascript tests

(cherry picked from commit ea1bc99c)

(cherry picked from commit d558fbef)

Issue #2797721 by jp.stacey: Custom form handler's submitForm not called when using example in documentation

(cherry picked from commit 85a227f7)

Issue #2777451 by markdorison, er.pushpinderrana, alexpott: @see references not forming links in documentation

(cherry picked from commit d262018e)

(cherry picked from commit 493eac19)

Issue #2716661 by anoopjohn: Fix 'Drupal.Commenting.FunctionComment' coding standard - Issues related to @see references

Issue #2700661 by anoopjohn: Ensure core compliance to Drupal.Commenting.FunctionComment.ParamCommentIndentation (part 1).

Issue #2658412 by leolando.tan, lokapujya, rakesh.gectcr, harsha012, thisisit, zweishar, miteshmap: Config API topic makes no mention of getEditable()

Issue #2680307 by metzlerd, jhodgdon: Direct people to Services and Elements pages on API sites in a clearer way

Issue #2571845 by drupal.ninja03, hussainweb, anil280988, snehi, jhodgdon, GoZ, stefan.r: Links to wikipedia/php.net should be part of the actual t() string so they can be localized

Issue #2603818 by jhodgdon, beejeebus, blackra: Add defgroups for listing page headers for api.drupal.org

Issue #2487588 by YesCT, Leksat, Schnitzel, alexpott, anavarre, xjm: Move CMI import/export directory "staging" to "sync", as it is confused with staging environments

Issue #2112679 by Berdir, damiankloip, nlisgo, krlucas, lokapujya, m1r1k, piyuesh23, blueminds, stefan.r, subhojit777, dawehner, kerby70, Dustin LeBlanc, znerol, JeroenT, borisson_, scor, amitgoyal, s_leu: getUsername() should return the username getDisplayName() for the formatted user name

Issue #2547707 by kekkis, screon, deepakaryan1988, latikas, jhodgdon, hussainweb, teemuaro, Crell, HeimdallJHM: Split routing documentation out of menu.api.php

Issue #2349431 by talhaparacha, Cyberwolf, bhavinvora, pjonckiere: Docs mention support for PUT instead of POST

Issue #2545958 by pjonckiere, jhodgdon, matslats: Module/profile use of config/optional is apparently not documented

Issue #2541432 by Wim Leers: Follow-up for #2231595: Document why ChainedFastBackend cannot use BackendChain

Issue #2493911 by dawehner, larowlan, damiankloip, hussainweb, jibran, cilefen, benjy, iMiksu, mtdowling: Update guzzle, goutte and mink-goutte-driver to the latest release

Issue #2408013 by Aki Tendo, alexpott, Fabianx, dawehner, Crell, jhodgdon, Wim Leers, aspilicious: Adding Assertions to Drupal - Test Tools

Issue #2502785 by dawehner, effulgentsia, tim.plunkett, amateescu, Fabianx, Wim Leers, catch, dsnopek, EclipseGc, yched, Berdir, larowlan, mondrake, olli: Remove support for $form_state->setCached() for GET requests

Issue #2354889 by larowlan, dawehner, lauriii, Berdir, catch, martin107, pfrenssen, EclipseGc, Fabianx, Wim Leers, dsnopek, jibran, tim.plunkett, andypost: Make block context faster by removing onBlock event and replace it with loading from a ContextManager

Issue #2500443 by jhodgdon, Wim Leers: Cache API topic says nothing about cache context, add something

Issue #2401843 by lahoosascoots, jhodgdon: Move all *.api.php files except system.api.php out of system module directory

Issue #2195083 by Les Lim, ParisLiakos, Xano, gaurav_varshney, ravi.khetri, fago, jain_deepak: Add a dedicated @Constraint annotation class

Issue #2478119 by znerol, andypost: Replace references to Session Manager with references to Session

Issue #2420737 by rodrigoaguilera, Pere Orga, Gábor Hojtsy, maxocub, jhodgdon, penyaskito, plach, danigrrl: Differences in dynamic language names are confusing in views, content, etc

Issue #2491155 by mikeburrelljr, Mac_Weber, opdavies: Update drupal.org and kernel.org URLs in core modules (Follow-up to 2489912)

Issue #2447365 by JacobSanford, klausi, dawehner, jhodgdon, webchick: Let's explain in DestructableInterface why it is useful