Fix file-names.md to render correctly

Author: gsnedders

docs/_writing-tests/file-names.md

@@ -8,43 +8,51 @@ The test filename is significant in determining the type of test it
 contains, and enabling specific optional features. This page documents
 the various flags avaiable and their meaning.
 
+
 ### Test Type
 
 These flags must be the last element in the filename before the
 extension e.g. `foo-manual.html` will indicate a manual test, but
 `foo-manual-other.html` will not. Unlike test features, test types
 are mutually exclusive.
 
-<dl>
-  <dt>`-manual`
-  <dd><p>Indicates that a test is a non-automated test.
-  <dt>`-support`
-  <dd><p>Indicates that a file is not a test but a support file.
-         Not required for files in a directory called `resources`,
-         `tools` or `support`.
-  <dt>`-visual`
-  <dd><p>Indicates that a file is a visual test.
-</dl>
+
+`-manual`
+ : Indicates that a test is a non-automated test.
+
+`-support`
+ : Indicates that a file is not a test but a support file.  Not
+   required for files in a directory called `resources`, `tools` or
+   `support`.
+
+`-visual`
+ : Indicates that a file is a visual test.
+
 
 ### Test Features
 
 These flags are preceded by a `.` in the filename, and must
 themselves precede any test type flag, but are otherwise unordered.
 
-<dl>
-  <dt>`.https`
-  <dd><p>Indicates that a test is loaded over HTTPS.
-  <dt>`.sub`
-  <dd><p>Indicates that a test uses the
-         <a href="https://wptserve.readthedocs.io/en/latest/pipes.html#sub">
-         server-side substitution</a> feature.
-  <dt>`.window`
-  <dd><p>(js files only) Indicates that the file generates a test in
-  which it is run in a Window environment.
-  <dt>`.worker`
-  <dd><p>(js files only) Indicates that the file generates a test in
-  which it is run in a dedicated worker environment.
-  <dt>`.any`
-  <dd><p>(js files only) Indicates that the file generates tests in
-  which it is run in Window and dedicated worker environments.
-</dl>
+
+`.https`
+ : Indicates that a test is loaded over HTTPS.
+
+`.sub`
+ : Indicates that a test uses the [server-side substitution][]
+   feature.
+
+`.window`
+ : (js files only) Indicates that the file generates a test in which
+    it is run in a Window environment.
+
+`.worker`
+ : (js files only) Indicates that the file generates a test in which
+    it is run in a dedicated worker environment.
+
+`.any`
+ : (js files only) Indicates that the file generates tests in which it
+    is run in Window and dedicated worker environments.
+
+
+[server-side substitution]: https://wptserve.readthedocs.io/en/latest/pipes.html#sub