Fix proof-pr dogfood command formatting

Author: saagpatel

docs/proof-pr-dogfood.md

@@ -11,11 +11,21 @@ environment and render the proof block from a generated receipt:
 
 ```bash
 python3 -m venv /tmp/gra-proof-pr-venv
-/tmp/gra-proof-pr-venv/bin/python -m pip install   git+https://github.com/saagpatel/proof-pr.git@v0.2.7
-/tmp/gra-proof-pr-venv/bin/proof-pr init   --cwd .   --tier T1   --summary "Short PR summary"   --output /tmp/gra-proof-pr.json
-/tmp/gra-proof-pr-venv/bin/proof-pr collect   /tmp/gra-proof-pr.json   --cwd .
-/tmp/gra-proof-pr-venv/bin/proof-pr render   /tmp/gra-proof-pr.json
-/tmp/gra-proof-pr-venv/bin/proof-pr receipt-hygiene   /tmp/gra-proof-pr.json   --explain
+/tmp/gra-proof-pr-venv/bin/python -m pip install \
+  git+https://github.com/saagpatel/proof-pr.git@v0.2.7
+/tmp/gra-proof-pr-venv/bin/proof-pr init \
+  --cwd . \
+  --tier T1 \
+  --summary "Short PR summary" \
+  --output /tmp/gra-proof-pr.json
+/tmp/gra-proof-pr-venv/bin/proof-pr collect \
+  /tmp/gra-proof-pr.json \
+  --cwd .
+/tmp/gra-proof-pr-venv/bin/proof-pr render \
+  /tmp/gra-proof-pr.json
+/tmp/gra-proof-pr-venv/bin/proof-pr receipt-hygiene \
+  /tmp/gra-proof-pr.json \
+  --explain
 ```
 
 `receipt-hygiene --explain` is the author-facing nudge for incomplete receipts.