Upgrade notes used to live in one global migrations/ directory, mixed
across all packages, while database/ and utils/ already carried their own
upgrading.texy. This consolidates everything on the per-package model, so
the notes sit next to the package they describe.

- add upgrading.texy to 15 packages (cs+en), sections ordered from the
newest version down to the oldest
- migrations/ becomes a lightweight hub: how to upgrade + links to the
per-package pages; the migrations: URL keeps working
- drop the pre-componentization guides (2.0-2.2). Nette split into
separate packages in 2.2, so per-package notes start at 2.3
- drop the balast: minimum PHP versions, composer.json version blocks,
composer-frontline.php and the cosmetic I-prefix interface renames
- use the term "upgrading" rather than "migration"; migration now only
means switching technology, as in Latte's cookbook
- link Upgrading from the packages' left menus

Incorporates the docs from #1079, verified against the plugin's
"added host option and normalized dev server URL" change: host option,
0.0.0.0/true normalization to localhost, CORS/allowedHosts handling.

- fix Czech grammar "ve chvíli, kde" -> "kdy" and unify tab/záložka wording
- use config.ini with parse_ini_file (NEON is not an INI format)
- document limitations: non-isolated stat functions, unlink on Windows, write rollback

- fix SMTP TLS default port (code defaults to 25, not 587)
- fix 'secure' description (deprecated alias of 'encryption', not value 'ssl')
- cs: add 'localhost' fallback for clientHost default
- document Message setters: addReplyTo(), setReturnPath(), setPriority() + priority constants
- document addEmbeddedFile() and SendmailMailer::setEnvelopeSender()
- expand FallbackMailer: $onFailure, addMailer(), FallbackMailerException
- document redirect/debugger config options

- decode(): parameter renamed $neon → $input to match the actual
signature (Neon::decode(string $input)); the old name broke named
arguments
- string quoting: added the reserved backtick to the list of characters
that require quoting (excluded by the lexer literal pattern)
- neon-lint: documented the optional [--debug] flag shown in its usage

Corrected untrue claims (dev server detection, type=module, what can be
loaded in production), broken examples (@s3mapper, extension option,
{preload} outputs), split mixed PHP/Latte code blocks, and fixed Czech
typos, mistranslations and broken links.

Documentation for the nette/command-line package (v1.x): Parser for
switches, options and positional arguments, and Console for colorful
ANSI terminal output. Adds meta.json plus aligned en/ and cs/ @home.texy.