NamespaceMap: fix TODO; "ElementID" -> "Element ID" (#821)

* Remove TODO and fix caps

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

* Use named link

Also use 4-space indent for bullet list, to keep the multiple paragraphs rendered correctly.

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

* Point to HTML version of serialization instead of GitHub repo

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

* Update model/Core/Classes/NamespaceMap.md

Co-authored-by: Alexios Zavras (zvr) <zvr+git@zvr.gr>
Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

* Update model/Core/Classes/NamespaceMap.md

Co-authored-by: Alexios Zavras (zvr) <zvr+git@zvr.gr>
Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

* "ElementID" -> "Element ID" Small grammar revision

ElementID is not a specific name anywhere in the model (possibly an externalSpdxId ?)

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

* "External Map" -> "external map"

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

---------

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>
Co-authored-by: Alexios Zavras (zvr) <zvr+git@zvr.gr>

model/Core/Classes/ExternalMap.md

@@ -4,11 +4,12 @@ SPDX-License-Identifier: Community-Spec-1.0
 
 ## Summary
 
-A map of Element identifiers that are used within a Document but defined external to that Document.
+A map of Element identifiers that are used within a Document but defined
+external to that Document.
 
 ## Description
 
-An External Map is a map of Element identifiers that are used within a Document
+An external map is a map of Element identifiers that are used within a Document
 but defined external to that Document.
 The external map provides details about the externally-defined Element
 such as its provenance, where to retrieve it, and how to verify its integrity.

model/Core/Classes/NamespaceMap.md

@@ -8,45 +8,45 @@ A mapping between prefixes and namespace partial URIs.
 
 ## Description
 
-A namespace map allows the creator of a collection of Elements that could be
-serialized to suggest a set of shorter identifiers ("prefixes") for particular
-namespace portions of ElementIDs to be used in SPDX content serialization in
-order to provide a more human-readable and smaller serialized representation of
-the Elements.
+A namespace map allows the creator of a collection of serializable Elements
+to suggest shorter identifiers ("prefixes") for specific namespace portions
+of Element IDs. This map is used in SPDX content serialization to provide
+a more human-readable and smaller serialized representation of the Elements.
 
 For details of how NamespaceMap content is to be serialized please refer to
-general SPDX serialization guidance at
-<https://github.com/spdx/spdx-3-model/blob/main/serialization/README.md>
-and the various serialization format specific .md filed under
-<https://github.com/spdx/spdx-3-model/tree/main/serialization>
-(TODO: update the URLs as soon as the context is publicly available)
+the [Model and serializations](../../../docs/serializations.md) clause
+and the various serialization format-specific files within the
+[spdx-3-model repository](https://github.com/spdx/spdx-3-model/tree/main/serialization).
 
 Namespace maps support a variety of relevant use cases such as:
 
 1. An SPDX content producer wishing to provide clarity of their serialization
-  of an SPDX 2.X simple style collection where all content is newly minted and
-  a single prefix-namespace is used. The consumer of SPDX content wishes to
-  preserve the name space mapping provided by such a producer. In this case,
-  the consumer would record the namespace map prefixes in the NamespaceMap such
-  that subsequent serializations could reproduce the prefixes / namespaces in
-  the native serialization format.
+    of an SPDX 2.X simple style collection where all content is newly minted
+    and a single prefix-namespace is used. The consumer of SPDX content wishes
+    to preserve the name space mapping provided by such a producer.
+
+    In this case, the consumer would record the namespace map prefixes in the
+    NamespaceMap such that subsequent serializations could reproduce the
+    prefixes / namespaces in the native serialization format.
 
 2. An SPDX content producer wishing to maintain consistent prefix use and
-  understanding across multiple different serialization formats of the produced
-  content.
-  For example, an SBOM producer wishes to share/publish the SBOM as JSON-LD and
-  XML. The producer can specify the preferred prefix mappings in the native
-  serialization format using information from a single Namespacemap accessible
-  local to the producer.
+    understanding across multiple different serialization formats of the
+    produced content.
+
+    For example, an SBOM producer wishes to share/publish the SBOM as JSON-LD
+    and XML. The producer can specify the preferred prefix mappings in the
+    native serialization format using information from a single NamespaceMap
+    accessible local to the producer.
 
 3. An SPDX content consumer/producer wishing to maintain consistent prefix use
-  while round tripping from SPDX content received, deserialized,
-  modified/extended in some way, and then reserialized in the same
-  serialization form.
-  In this case the prefix-namespace mappings utilized in the content are
-  transformed from the original native namespace/prefix into the in memory
-  NamespaceMap then transformed from the NamespaceMap back into the resultant
-  serialization native namespace / prefix format.
+    while round tripping from SPDX content received, deserialized,
+    modified/extended in some way, and then reserialized in the same
+    serialization form.
+
+    In this case the prefix-namespace mappings utilized in the content are
+    transformed from the original native namespace/prefix into the in memory
+    NamespaceMap then transformed from the NamespaceMap back into the resultant
+    serialization native namespace / prefix format.
 
 ## Metadata
 

model/Core/Properties/namespace.md

@@ -5,12 +5,12 @@ SPDX-License-Identifier: Community-Spec-1.0
 ## Summary
 
 Provides an unambiguous mechanism for conveying a URI fragment portion of an
-ElementID.
+Element ID.
 
 ## Description
 
 A namespace provides an unambiguous mechanism for conveying a URI fragment
-portion of an ElementID.
+portion of an Element ID.
 
 ## Metadata