Add slop scan tool to contributing docs (#1740)

### Description of Changes

- Credit to @gebastel for original PR
  - Closes #1314
  - Closes #1116

Reviewed-on: https://codeberg.org/ethical-foss/open-slopware/pulls/1740

CONTRIBUTING.md

@@ -7,6 +7,7 @@
   * [For Adding or Updating Tainted Software](#for-adding-or-updating-tainted-software)
     * [Other tips for keeping the repo tidy](#other-tips-for-keeping-the-repo-tidy)
     * [Criteria](#criteria)
+      * [Last Untainted Commit/Version](#last-untainted-commit-version)
       * [Alternatives](#alternatives)
     * [Style guide](#style-guide)
     * [Removal of "Tainted" Status](#removal-of-tainted-status)
@@ -80,6 +81,19 @@ Please don't submit social media posts as evidence unless it is a post *by a mai
 
 We do not currently accept adult content in this list, but if you have a similar list that does accept such content, and you meet the [Rules for self submission](#rules-for-self-submission), please feel free to submit an issue to ask to be added to our sibling repos, where we can link to your repo.
 
+#### Last Untainted Commit/Version
+
+We ask that contributors please add the last untainted commit when submitting tainted software if there are already tainted commits in the repo.
+
+If you quickly want to scan a git repo that isn't on this list or you'd like to find the last untainted commit, you could use [**Repo-Slopscore**](https://codeberg.org/polyphony/repo-slopscore) to do an initial evaluation. The tool checks if specific files exist in a repo or the git history/ignore file contains specific strings. It does not scan the source code itself and could sometimes trigger false positives or false negatives. *Please verify the information through careful research.* You can run it on your own computer or check out the [**public instance**](https://slopscan.ava.pet/).
+
+> [!NOTE]
+> * Please only use slopscore/slopscan for popular repos you personally use(d). We do not want people running this on every repo on GitHub as that would create too much work for the few humans that maintain this repo.
+> * Please also do not use slopscan.ava.pet as your evidence link when submitting PRs or Issues to this repo (though you can use it for research). We'd prefer direct links to tainted commits in the tainted repo so we can properly check them.
+> * Slopscore/slopscan are irrelavant once a repo creates an Anti-AI policy.
+
+You can also find past discussion of how to find the untainted commit in [#1116](https://codeberg.org/ethical-foss/open-slopware/issues/1116).
+
 #### Alternatives
 
 Alternatives should not contain any slop as defined by our tagging system above.

STYLE.md

@@ -23,7 +23,7 @@ Make sure to format your table like below (note that it is alphabetized by softw
 
 **Name column**: should be the name of software linked to their git repo (or other software forge if they don't use git).
 
-**Last Untainted Version/Commit**: should be the last commit before AI started being used in the repo. You can provide both the version and a commit hash, but if you can only provide one, please prefer using the version. (Reminder: This is meant for forking only, as running old software comes with security risks.) If the project is [![Vibecoded](./badges/vibecoded.svg)](https://codeberg.org/ethical-foss/open-slopware##vibecoded), you can just use the word "None" for the Last Untainted Version/Commit. You must provide something (even "None" if Vibecoded) *either* for this column, or for the alternatives column - unless there is already an "Alternatives" note. See also: [tips for finding the last untainted commit](https://codeberg.org/ethical-foss/open-slopware/issues/1116).
+**Last Untainted Version/Commit**: should be the last commit before AI started being used in the repo. You can provide both the version and a commit hash, but if you can only provide one, please prefer using the version. (Reminder: This is meant for forking only, as running old software comes with security risks.) If the project is [![Vibecoded](./badges/vibecoded.svg)](https://codeberg.org/ethical-foss/open-slopware##vibecoded), you can just use the word "None" for the Last Untainted Version/Commit. You must provide something (even "None" if Vibecoded) *either* for this column, or for the alternatives column - unless there is already an "Alternatives" note. See also: [tips for finding the last untainted commit](https://codeberg.org/ethical-foss/open-slopware/src/branch/main/CONTRIBUTING.md#last-untainted-commit-version).
 
 **Evidence column**: should contain one or more of the following tags (followed by up to *three* numbered evidence links in parentheses separated by a comma followed by a whitespace):