docs: update specs to treat DataJoint 2.0 as current

- semantic-matching.md: clarify applies to all binary operators, not just joins
- semantic-matching.md: change "replacing current rules" to "replaces pre-2.0 rules"
- job-metadata.md: rename "Current/Proposed implementation" to "Pre-2.0/DataJoint 2.0 implementation"

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dimitri-yatsenko

src/reference/specs/job-metadata.md

@@ -157,15 +157,15 @@ SELECT * FROM table_a NATURAL JOIN table_b
 
 Hidden attributes must be excluded from all binary operator considerations. The result of a join does not preserve hidden attributes from its operands.
 
-**Current implementation:**
+**Pre-2.0 implementation:**
 ```python
 def from_clause(self):
     clause = next(support)
     for s, left in zip(support, self._left):
         clause += " NATURAL{left} JOIN {clause}".format(...)
 ```
 
-**Proposed implementation:**
+**DataJoint 2.0 implementation:**
 ```python
 def from_clause(self):
     clause = next(support)

src/reference/specs/semantic-matching.md

@@ -1,13 +1,13 @@
-# Semantic Matching for Joins - Specification
+# Semantic Matching - Specification
 
 ## Overview
 
-This document specifies **semantic matching** for joins in DataJoint 2.0, replacing the current name-based matching rules. Semantic matching ensures that attributes are only matched when they share both the same name and the same **lineage** (origin), preventing accidental joins on unrelated attributes that happen to share names.
+This document specifies **semantic matching** for binary operators in DataJoint 2.0. Semantic matching ensures that attributes are only matched when they share both the same name and the same **lineage** (origin), preventing accidental matches on unrelated attributes that happen to share names. This replaces the name-based matching rules from pre-2.0 versions.
 
 ### Goals
 
-1. **Prevent incorrect joins** on attributes that share names but represent different entities
-2. **Enable valid joins** that are currently blocked due to overly restrictive rules
+1. **Prevent incorrect matches** on attributes that share names but represent different entities
+2. **Enable valid operations** that were previously blocked due to overly restrictive rules
 3. **Maintain backward compatibility** for well-designed schemas
 4. **Provide clear error messages** when semantic conflicts are detected