Fix last remaining broken links (#1332)

Author: JPryce-Aklundh

modules/ROOT/pages/appendix/gql-conformance/supported-optional.adoc

@@ -106,7 +106,7 @@ These codes order the features in the table below.
 
 | GD01
 | Updatable graphs
-| xref:clauses/clause-composition.adoc#writing-clauses[Cypher clauses -> Writing clauses]
+| xref:clauses/index.adoc#writing-clauses[Cypher clauses -> Writing clauses]
 | * Feature GD01 implies compliance with GQL feature GT01, "Explicit transaction commands", which states that conforming languages shall contain the following transaction control commands: `START TRANSACTION`, `ROLLBACK`, and `COMMIT`.
 These are not present in Cypher.
 However, Neo4j offers transaction management through the link:{neo4j-docs-base-uri}/create-applications[driver] transaction API.

modules/ROOT/pages/expressions/predicates/type-predicate-expressions.adoc

@@ -64,8 +64,8 @@ RETURN val, val IS NOT :: STRING AS notString
 |===
 
 
-[[type-predicate-NULL]]
-== Type predicate expressions for NULL
+[[type-predicate-null]]
+== Type predicate expressions for null
 
 All Cypher types includes the `null` value.
 Type predicate expressions can be appended with `NOT NULL`.

modules/ROOT/pages/patterns/match-modes.adoc

@@ -95,7 +95,7 @@ RETURN pathCount,
        [r IN relationships(samplePath) | r.id] AS samplePathBridges
 ----
 
-<1> The xref:functions/list.adoc#functions-collect[`collect()`] function collects all paths and `[0]` takes the first entry as the `samplePath`.
+<1> The xref:functions/aggregating.adoc#functions-collect[`collect()`] function collects all paths and `[0]` takes the first entry as the `samplePath`.
 
 .Result
 [role="queryresult",options="header,footer",cols="3*<m"]