fix: wiki-ingest and wiki-manage call xref add with --rel, not --rel-a/--rel-b (#174)

Files changed:
- CHANGES.md
- VERSION
- instructions/wiki-ingest/SKILL.md
- instructions/wiki-manage/SKILL.md

instructions/wiki-ingest/SKILL.md

@@ -343,11 +343,13 @@ validator complains - and the ticked list is the only record that they happened.
 9. **Cross-reference.**
 
    ```bash
-   tools/wikitool xref add --a "<A>" --b "<B>" --rel-a "<label>" --rel-b "<label>"
+   tools/wikitool xref add --a "<A>" --b "<B>" --rel "<label>"   # [A] <label> [B]
    tools/wikitool xref link-source --source "Source - <Title>" --entities A,B,C
    ```
 
-   The second links the new source to everything it backs in one pass.
+   The first declares one edge, on A only; which way it reads, and when the reverse edge earns a
+   call of its own, is `kb/CONTRACT.md` § Linking. The second links the new source to everything
+   it backs in one pass.
 
 10. **Check coverage.**
 

instructions/wiki-manage/SKILL.md

@@ -56,10 +56,11 @@ requirements come from `tools/wikitool types describe <type>`.
 6. **Cross-reference.**
 
    ```bash
-   tools/wikitool xref add --a "<A>" --b "<B>" --rel-a "<label>" --rel-b "<label>"
+   tools/wikitool xref add --a "<A>" --b "<B>" --rel "<label>"   # [A] <label> [B]
    ```
 
-   One per relationship. Never hand-edit `related:`.
+   One per relationship, on A only; which way it reads, and when the reverse edge earns a call of
+   its own, is `kb/CONTRACT.md` § Linking. Never hand-edit `related:`.
 
 7. **Close out.** `instructions/publish-cycle.md`, `--op create`.