docs: teach Hugging Face Write token setup for Community PRs

README.md

@@ -38,6 +38,35 @@ Notebook: [Example Data](https://github.com/electronmicroscopy/quantem.widget/bl
 Anyone with a Hugging Face account can add data. We follow a pull request
 process. Do not use `quantem.widget.io.upload`.
 
+Downloads need no token. Opening a pull request does. Create an account,
+then a token at
+[huggingface.co/settings/tokens](https://huggingface.co/settings/tokens).
+Use a **Write** token (classic). A **Read** token can download; it cannot
+open a PR. A fine-grained token also works if `--create-pr` is allowed on
+a public dataset. You do not need collaborator access to this repo.
+
+```bash
+pip install huggingface_hub   # skip if `hf` is already on PATH
+hf auth login
+```
+
+Paste the token. The prompt hides it. When asked `Add token as git
+credential? [y/N]`, answer `n`. `hf upload` reads
+`~/.cache/huggingface/token`. You do not need a git credential helper.
+Ignore any hint to run `git config --global credential.helper store`.
+
+```bash
+hf auth whoami
+```
+
+That should print your username. If you already logged in with a Read
+token, run `hf auth login --force` and paste a Write token. If
+`--create-pr` returns 403 after a valid login, the token is Read or the
+fine-grained scopes omit Community PRs; make a Write token and login
+again. On SSH (no browser on that machine), paste a token. Do not use the
+browser login unless the browser and `hf` run on the same machine. Do not
+commit the token.
+
 A PR is the data file(s) plus one `meta.json`. Example already on the hub
 (2 files):
 
@@ -93,13 +122,12 @@ Processed float data uses `"float32"`. Read both values from the file
 ```
 
 `source` is microscope, facility, and original file. `date` is acquisition
-day (`YYYY-MM-DD`). `permission.received` must be `true`. `from` is who granted the MIcan yT share (one name or several). `collectors` is who used the
-instrument (one name or several). `permission.date` is when that share was
-granted.
+day (`YYYY-MM-DD`). `permission.received` must be `true`. `from` is who granted the share (one name or several). `collectors` is who
+used the instrument (one name or several). `permission.date` is when that
+share was granted.
 
 ```bash
 python templates/check_meta.py ./gold-512-bin4
-hf auth login
 hf upload bobleesj/quantem-data ./gold-512-bin4 \
   widget-tutorials/show4dstem/gold-512-bin4/full \
   --repo-type dataset --create-pr