C#/Java: Fix some QL doc spelling typos.

Author: michaelnebel

csharp/ql/lib/semmle/code/csharp/dataflow/ExternalFlow.qll

@@ -247,7 +247,7 @@ predicate summaryModel(
   )
 }
 
-/** Holds is a summary model exists indicating there is no flow for the given parameters. */
+/** Holds if a summary model exists indicating there is no flow for the given parameters. */
 predicate negativeSummaryModel(
   string namespace, string type, string name, string signature, string provenance
 ) {

csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll

@@ -173,7 +173,7 @@ module Ssa {
     }
 
     /**
-     * Holds is this SSA definition is live at the end of basic block `bb`.
+     * Holds if this SSA definition is live at the end of basic block `bb`.
      * That is, this definition reaches the end of basic block `bb`, at which
      * point it is still live, without crossing another SSA definition of the
      * same source variable.

java/ql/lib/semmle/code/java/dataflow/ExternalFlow.qll

@@ -507,7 +507,7 @@ predicate summaryModel(
   row.splitAt(";", 9) = provenance
 }
 
-/** Holds is a summary model exists indicating there is no flow for the given parameters. */
+/** Holds if a summary model exists indicating there is no flow for the given parameters. */
 predicate negativeSummaryModel(
   string namespace, string type, string name, string signature, string provenance
 ) {

ruby/ql/lib/codeql/ruby/ast/Variable.qll

@@ -63,7 +63,7 @@ class GlobalVariable extends Variable instanceof GlobalVariableImpl {
 
 /** An instance variable. */
 class InstanceVariable extends Variable instanceof InstanceVariableImpl {
-  /** Holds is this variable is a class instance variable. */
+  /** Holds if this variable is a class instance variable. */
   final predicate isClassInstanceVariable() { super.isClassInstanceVariable() }
 
   final override InstanceVariableAccess getAnAccess() { result.getVariable() = this }