docs: fix README_NBA_LOGOS and PLUGIN_CONFIGURATION_GUIDE

scripts/README_NBA_LOGOS.md
- "python download_nba_logos.py" — wrong on two counts. The script
  is at scripts/download_nba_logos.py (not the project root), and
  "python" is Python 2 on most systems. Replaced all 4 occurrences
  with "python3 scripts/download_nba_logos.py".
- The doc framed itself as the way to set up "the NBA leaderboard".
  The basketball/leaderboard functionality is now in the
  basketball-scoreboard and ledmatrix-leaderboard plugins (in the
  ledmatrix-plugins repo), which auto-download logos on first run.
  Reframed the script as a pre-population utility for offline / dev
  use cases.
- Bumped the documented Python minimum from 3.7 to 3.9 to match
  the rest of the project.

docs/PLUGIN_CONFIGURATION_GUIDE.md
- The "Plugin Manifest" example was missing 3 fields the plugin
  loader actually requires: id, entry_point, and class_name. A
  contributor copying this manifest verbatim would get
  PluginError("No class_name in manifest") at load time — the same
  loader bug already found in stock-news. Added all three.
- The same example showed config_schema as an inline object. The
  loader expects config_schema to be a file path string (e.g.
  "config_schema.json") with the actual schema in a separate JSON
  file — verified earlier in this audit. Fixed.
- Added a paragraph explaining the loader's required fields and
  the case-sensitivity rule on class_name (the bug that broke
  hello-world's manifest before this PR fixed it).
- "Plugin Manager Class" example had the wrong constructor
  signature: (config, display_manager, cache_manager, font_manager).
  The real BasePlugin.__init__ at base_plugin.py:53-60 takes
  (plugin_id, config, display_manager, cache_manager, plugin_manager).
  A copy-pasted example would TypeError on instantiation. Fixed,
  including a comment noting which attributes BasePlugin sets up.
- Renamed the example class from MyPluginManager to MyPlugin to
  match the project convention (XxxPlugin / XxxScoreboardPlugin
  in actual plugins).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/README_NBA_LOGOS.md

@@ -1,29 +1,40 @@
 # NBA Logo Downloader
 
-This script downloads all NBA team logos from the ESPN API and saves them in the `assets/sports/nba_logos/` directory for use with the NBA leaderboard.
+This script downloads all NBA team logos from the ESPN API and saves
+them in the `assets/sports/nba_logos/` directory.
+
+> **Heads up:** the NBA leaderboard and basketball scoreboards now
+> live as plugins in the
+> [`ledmatrix-plugins`](https://github.com/ChuckBuilds/ledmatrix-plugins)
+> repo (`basketball-scoreboard`, `ledmatrix-leaderboard`). Those
+> plugins download the logos they need automatically on first display.
+> This standalone script is mainly useful when you want to pre-populate
+> the assets directory ahead of time, or for development/debugging.
+
+All commands below should be run from the LEDMatrix project root.
 
 ## Usage
 
 ### Basic Usage
 ```bash
-python download_nba_logos.py
+python3 scripts/download_nba_logos.py
 ```
 
 ### Force Re-download
 If you want to re-download all logos (even if they already exist):
 ```bash
-python download_nba_logos.py --force
+python3 scripts/download_nba_logos.py --force
 ```
 
 ### Quiet Mode
 Reduce logging output:
 ```bash
-python download_nba_logos.py --quiet
+python3 scripts/download_nba_logos.py --quiet
 ```
 
 ### Combined Options
 ```bash
-python download_nba_logos.py --force --quiet
+python3 scripts/download_nba_logos.py --force --quiet
 ```
 
 ## What It Does
@@ -82,12 +93,14 @@ assets/sports/nba_logos/
 └── WAS.png  # Washington Wizards
 ```
 
-## Integration with NBA Leaderboard
+## Integration with NBA plugins
 
-Once the logos are downloaded, the NBA leaderboard will:
-- ✅ Use local logos instantly (no download delays)
-- ✅ Display team logos in the scrolling leaderboard
-- ✅ Show proper team branding for all 30 NBA teams
+Once the logos are in `assets/sports/nba_logos/`, both the
+`basketball-scoreboard` and `ledmatrix-leaderboard` plugins will pick
+them up automatically and skip their own first-run download. This is
+useful if you want to deploy a Pi without internet access to ESPN, or
+if you want to preview the display on your dev machine without
+waiting for downloads.
 
 ## Troubleshooting
 
@@ -102,6 +115,6 @@ This is normal - some teams might have temporary API issues or the ESPN API migh
 
 ## Requirements
 
-- Python 3.7+
-- `requests` library (should be installed with the project)
+- Python 3.9+ (matches the project's overall minimum)
+- `requests` library (already in `requirements.txt`)
 - Write access to `assets/sports/nba_logos/` directory