Fix scaladoc.

src/main/scala/catalyst/expressions/package.scala

@@ -8,24 +8,24 @@ package catalyst
  *
  * ==Standard Expressions==
  * A library of standard expressions (e.g., [[Add]], [[Equals]]), aggregates (e.g., SUM, COUNT), and other computations
- * (e.g. UDFs). Each type expression is capable of determining its output schema as a function of its children’s output
+ * (e.g. UDFs). Each expression type is capable of determining its output schema as a function of its children’s output
  * schema.
  *
  * ==Named Expressions==
- * Some expression are named and thus can be referenced by other operators in the dataflow graph. The two types of named
- * expressions are [[AttributeReference]]s and [[Alias]]es.  [[AttributeReference]]s refer to parts of the input tuple f
- * or a given operator and form the leaves of all expression trees.  Aliases assign a name to intermediate computations.
- * For example, in the SQL statement “SELECT a+b AS c FROM ...”, the expressions ‘a’ and ‘b’ would be represented by
- * AttributeReferences and ‘c’ would be represented by an Alias.
+ * Some expression are named and thus can be referenced by later operators in the dataflow graph. The two types of named
+ * expressions are [[AttributeReference]]s and [[Alias]]es.  [[AttributeReference]]s refer to attributes of the input tuple
+ * for a given operator and form the leaves of some expression trees.  Aliases assign a name to intermediate computations.
+ * For example, in the SQL statement `SELECT a+b AS c FROM ...`, the expressions `a` and `b` would be represented by
+ * `AttributeReferences` and `c` would be represented by an `Alias`.
  *
  * During [[analysis]], all named expressions are assigned a globally unique expression id, which can be used for equality
  * comparisons.  While the original names are kept around for debugging purposes, they should never be used to check
- * attribute equality, as plan transformations can result in the introduction of naming ambiguity.  For example,
- * consider a plan that contains subqueries, both of which are reading from the same table.  If an optimization removes
- * the subqueries, scoping information would be destroyed, eliminating the ability to reason about which subquery
- * produced a given attribute.
+ * if two attributes refer to the same value, as plan transformations can result in the introduction of naming ambiguity.
+ * For example, consider a plan that contains subqueries, both of which are reading from the same table.  If an
+ * optimization removesmthe subqueries, scoping information would be destroyed, eliminating the ability to reason about 
+ * which subquery produced a given attribute.
  *
  * ==Evaluation==
  * The result of expressions can be evaluated using the [[Evaluate]] object.
  */
-package object expressions
+package object expressions