[NO ISSUE] Fix Markdown errors in Data Model documentation

Change-Id: Iec17bc31981b83e996ec6628392eb045f703bb36
Reviewed-on: https://asterix-gerrit.ics.uci.edu/3028
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Dmitry Lychagin <dmitry.lychagin@couchbase.com>
diff --git a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_composite.md b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_composite.md
index 7ed4e34..92b0374 100644
--- a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_composite.md
+++ b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_composite.md
@@ -20,7 +20,7 @@
 
 ## <a id="DerivedTypes">Derived Types</a> ##
 
-### <a id="DerivedTypesObject">Object</a>###
+### <a id="DerivedTypesObject">Object</a> ###
 An `object` contains a set of fields, where each field is described by its name and type. An object type may be defined as either open or closed. Open objects (instances of open object types) are permitted to contain fields that are not part of the type definition, while closed objects do not permit their instances to carry extra fields. An example type definition for an object is:
 
         create type SoldierType as open {
@@ -38,7 +38,7 @@
 
 The first instance has all of the type's prescribed content. The second instance is missing the name field, which is fine because it is optional (due to the ?). The third instance has an extra field; that is fine because the type definition specifies that it is open (which is also true by default, if open is not specified). To more tightly control object content, specifying closed instead of open in the type definition for SoldierType would have made the third example instance an invalid instance of the type.
 
-### <a id="DerivedTypesArray">Array</a>###
+### <a id="DerivedTypesArray">Array</a> ###
 An `array` is a container that holds a fixed number of values. Array constructors are denoted by brackets: "[...]".
 
 An example would be
@@ -47,7 +47,7 @@
         ["alice", 123, "bob", null]
 
 
-### <a id="DerivedTypesMultiset">Multiset</a>###
+### <a id="DerivedTypesMultiset">Multiset</a> ###
 A `multiset` is a generalization of the concept of a set that, unlike a set, allows multiple instances of the multiset's elements.
  Multiset constructors are denoted by two opening curly braces followed by data and two closing curly braces, like "{{...}}".
 
diff --git a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_header.md b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_header.md
index 74bab7f..cc66a3f 100644
--- a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_header.md
+++ b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_header.md
@@ -39,7 +39,7 @@
     * [Duration/Year_month_duration/Day_time_duration](#PrimitiveTypesDuration)
     * [Interval](#PrimitiveTypesInterval)
     * [UUID](#PrimitiveTypesUUID)
-* [Incomplete Information Types] (#IncompleteInformationTypes)
+* [Incomplete Information Types](#IncompleteInformationTypes)
     * [Null](#IncompleteInformationTypesNull)
     * [Missing](#IncompleteInformationTypesMissing)
 * [Derived Types](#DerivedTypes)
diff --git a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_incomplete.md b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_incomplete.md
index da88ea0..c65ed85 100644
--- a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_incomplete.md
+++ b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_incomplete.md
@@ -17,7 +17,7 @@
  ! under the License.
  !-->
 
-## <a id="IncompleteInformationTypes">Incomplete Information Types</a>##
+## <a id="IncompleteInformationTypes">Incomplete Information Types</a> ##
 
 ### <a id="IncompleteInformationTypesNull">Null</a> ###
 `null` is a special value that is often used to represent an unknown value.
diff --git a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_common.md b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_common.md
index 8f9b28e..4c0b2e0 100644
--- a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_common.md
+++ b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_common.md
@@ -17,7 +17,7 @@
  ! under the License.
  !-->
 
-## <a id="PrimitiveTypes">Primitive Types</a>##
+## <a id="PrimitiveTypes">Primitive Types</a> ##
 
 ### <a id="PrimitiveTypesBoolean">Boolean</a> ###
 `boolean` data type can have one of the two values: _*true*_ or _*false*_.
diff --git a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_delta.md b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_delta.md
index 51aaed3..dc35381 100644
--- a/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_delta.md
+++ b/asterixdb/asterix-doc/src/main/markdown/datamodel/datamodel_primitive_delta.md
@@ -114,7 +114,7 @@
         { "v1": line("10.1234,1.11 0.102,-11.22"), "v2": line("0.1234,-1.0E-10 0.105,-1.02") }
 
 
-### <a id="PrimitiveTypesRectangle">Rectangle</a>###
+### <a id="PrimitiveTypesRectangle">Rectangle</a> ###
 `rectangle` consists of two points that represent the _*bottom left*_ and _*upper right*_ corners of a rectangle.
 
  * Example: