Bug 1852559 - Minor cleanup for the What is a Triaged Bug documentati…

…on. r=firefox-source-docs-reviewers,sylvestre DONTBUILD

Add a link for the first mention of "Severity", use upper cased
Severity more consistently, use "nor".

Differential Revision: https://phabricator.services.mozilla.com/D188288

docs/bug-mgmt/policies/triage-bugzilla.rst

@@ -12,10 +12,11 @@ What is a Triaged Bug
 
 The new definition of Triaged will be Firefox-related bugs of type
 ``defect`` where the component is not
-``UNTRIAGED``, and a severity value not equal to ``--`` or ``N/A``.
+``UNTRIAGED``, and a :ref:`Severity <Defect Severity>` value not equal
+to ``--`` or ``N/A``.
 
-Bugs of type Task or Enhancement may have a severity of ``N/A``,
-but defects must have a severity that is neither ``--`` or
+Bugs of type Task or Enhancement may have a Severity of ``N/A``,
+but defects must have a Severity that is neither ``--`` nor
 ``N/A``.
 
 Why Triage