docs(release): notes for v0.1.10

docs/releases/v0.1.10.md

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+**Credential plugins such as `tsh`, `aws` and `kubelogin` stay off the
+terminal**, so a login prompt no longer hangs k10s, and the plugin's own
+words, where it has any, say what to do. **Plugins that run a shell's `-c`
+script with options around `-c`, or through `env` or `busybox`, now get
+k10s's values through the environment too**, so a value from the cluster,
+such as a column's text, can no longer run as part of their script.
+
+## Credential plugins stay off the terminal ([#41](https://github.com/p10node/k10s/pull/41))
+
+Many kubeconfig users get their token from a program: `tsh kube credentials`
+(Teleport), `aws eks get-token`, `kubelogin`, `gke-gcloud-auth-plugin`.
+client-go handed that program the terminal's input whenever there was one, so
+under k10s a relogin or MFA prompt read keystrokes meant for k10s and wrote over
+the screen, and the session looked hung.
+
+- The plugin now runs without the terminal's input, as kubectl runs it when
+  stdin is taken: one that would have prompted fails at once instead of
+  waiting, and one that declares `interactiveMode: Always` is refused before it
+  runs.
+- What the plugin writes to stderr no longer lands on the screen. Its last line
+  becomes the No cluster reason, such as `credential plugin tsh: Having
+  problems with relogin, please use 'tsh login/tsh kube login' manually`,
+  instead of `exec: executable tsh failed with exit code 1`.
+- A slow plugin no longer turns into No cluster: when the first request times
+  out with a plugin in use, k10s asks once more, with the credentials the
+  plugin has fetched by then.
+- While k10s connects, the status line names the plugin it is waiting on.
+  `/setup` and
+  [docs/cluster-setup.md](https://github.com/p10node/k10s/blob/main/docs/cluster-setup.md)
+  have a section on credential plugins, with Teleport's caveats.
+
+## Values reach every `-c` script through the environment ([#40](https://github.com/p10node/k10s/pull/40))
+
+When a plugin's command is a shell with `-c`, k10s gives the script the values
+it fills in, such as `$NAME`, `$NAMESPACE` and `$COL-STATUS`, as environment
+variables, so the shell never reads a value as code. Until this release that
+held only when the script came right after the first option that holds `c`,
+such as `-c` or `-ec`, and the command itself was the shell. In these command
+lines k10s pasted the values into the script's text, and a value that held
+shell syntax ran as part of the script:
+
+- options between `-c` and the script: `sh -c -x '...'`,
+  `sh -c -o errexit '...'`, `sh -c -- '...'`;
+- a shell run through another program: `env bash -c '...'`,
+  `busybox sh -c '...'`.
+
+k10s now reads a shell's options the way the shells do, and finds the shell
+behind `env` and `busybox`. Arguments after the script, which the shell passes
+as `$0`, `$1` and so on, still get the values as text, so
+`sh -c '... "$1"' sh $NAME` works as before. When k10s cannot tell which
+argument is the script, every argument reads the values from the environment.
+
+`env -S` builds a command line of its own from a string and expands `${VAR}`
+in it, so the environment cannot keep a value out of it. As with `python3 -c`,
+what such a plugin does with the values is up to the plugin.
+[docs/plugins.md](https://github.com/p10node/k10s/blob/main/docs/plugins.md)
+and [SECURITY.md](https://github.com/p10node/k10s/blob/main/SECURITY.md) say
+how values reach a `-c` script. Thanks to
+[@pierreneter](https://github.com/pierreneter), who found it while reviewing
+[#28](https://github.com/p10node/k10s/pull/28).
+
+## Also
+
+- `k10s --help` says that read-only mode blocks every external plugin, as it
+  does, not only dangerous ones ([#39](https://github.com/p10node/k10s/pull/39)).
+- If k10s crashes, the stack trace is printed once the terminal is back to
+  normal, ready for a bug report ([#44](https://github.com/p10node/k10s/pull/44)).
+
+## Upgrading
+
+A credential plugin can no longer ask for anything while k10s runs: log in with
+it first, or in another shell, then press `r`.
+
+A plugin whose `-c` script comes after options, or whose shell runs through
+`env` or `busybox`, now reads its values from the environment, as a plain
+`sh -c '...'` plugin already did. Quote them in the script as any shell
+variable: `"$NAME"`, not `'$NAME'`, which the shell leaves as it is. A command
+line k10s cannot read, such as one with bash's `-O`, gets the environment in
+every argument, so a value passed as `$1` arrives as `$NAME`: set such an
+option inside the script instead, for example with `shopt -s extglob`.
+
+govulncheck reports none for this release.
+
+`/update` from inside k10s, checksum-verified, atomic, offers to restart into
+the new binary; a Homebrew install upgrades with `brew upgrade k10s`.
+
+```bash
+curl -fsSL https://p10node.com/k10s/install.sh | sh
+brew install p10node/tap/k10s
+go install github.com/p10node/k10s@latest
+gh attestation verify k10s_v0.1.10_<os>_<arch>.tar.gz --repo p10node/k10s   # .zip on Windows
+```
+
+Issues and friction reports: https://github.com/p10node/k10s/issues