docs: shorten help and migration texts to gh-like brevity

Long texts no longer restate the flag list, the instance selection
of tea help environment, the config keys with descriptions or the
team argument rules shown under ARGUMENTS; webhook events come from
services.WebhookEvents; the migration guide refers to tea help
formatting for the terminal layout.

Signed-off-by: bircni <bircni@icloud.com>

docs/migration-1.0.md

@@ -295,29 +295,13 @@ names; `--jq` / `-q` filters the result and implies `--json`. Commands that
 produce no resource, such as deletes, reject `--json` with a usage error instead
 of printing nothing. See `tea help formatting`.
 
-Lists follow gh. On a terminal they print a "Showing 30 of 112 open issues in
-alice/project" line, an uppercase header row and columns fitted to the terminal
-width, with times relative ("about 3 hours ago"), states colored and the first
-column linked to the web page (`tea config set hyperlinks never` turns the links
-off). An empty list prints a message on stderr and exits 0. When stdout is not a
-terminal, lists print tab-separated values without header, color or links, with
-times in RFC 3339 UTC and stable columns, so `cut -f1` works; a `--page` hint
-goes to stderr when more results follow. Still prefer `--json` in scripts: the
-columns may change. Tabs and line breaks in list cells become spaces, and
-control characters such as escape sequences are dropped from all human output,
-bodies included.
-
-Commands that change resources report each change on stderr, such as
-`✓ Closed issue alice/project#5 (Fix login)` or `! … is already closed`, only
-when stdout is a terminal. Create commands print the URL of the new resource
-on stdout, so `url=$(tea issue create …)` works; other changes print nothing
-when piped. With `--json` they print the changed resource instead.
-
-Issue, pull request, release and comment bodies are rendered as Markdown on a
-terminal and printed as written when piped; `tea config set markdown raw` always
-prints them as written. Long output on a terminal goes through a pager
-(`TEA_PAGER`, the `pager` preference or `PAGER`). Each command starts the pager
-at most once.
+When stdout is not a terminal, lists print tab-separated values without header,
+color or links, with times in RFC 3339 UTC, and a `--page` hint goes to stderr;
+prefer `--json` in scripts. Commands that change resources report each change on
+stderr only on a terminal. Create commands print the URL of the new resource on
+stdout, so `url=$(tea issue create …)` works; other changes print nothing when
+piped. Bodies are rendered as Markdown only on a terminal (`tea config set
+markdown raw` turns this off). See `tea help formatting` for the terminal layout.
 
 ## Exit codes