doc: link to plugin behavior docs even if there are no caveats.

Just in case the File Formats table would get outdated. Or if people
would want to know what exactly the plugin does extra.

doc/file-formats.dox

@@ -74,7 +74,7 @@ Together with @ref file-formats-scene-importers "scene importers" derived from
 <th>Basis Universal (`*.basis`)</th>
 <td>`BasisImporter`</td>
 <td>@ref Trade::BasisImporter "BasisImporter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-BasisImporter-behavior "none"</td>
 <td class="m-text-center m-success">bundleable, tiny</td>
 <td class="m-text-center m-success">Apache-2.0</td>
 </tr>
@@ -90,7 +90,7 @@ Together with @ref file-formats-scene-importers "scene importers" derived from
 </tr>
 <tr>
 <td>@ref Trade::DevIlImageImporter "DevIlImageImporter"</td>
-<td class="m-text-center m-dim">unknown</td>
+<td class="m-text-center m-dim">@ref Trade-DevIlImageImporter-behavior "unknown"</td>
 <td class="m-text-center m-danger">external</td>
 <td class="m-text-center m-warning">LGPLv2.1</td>
 </tr>
@@ -148,13 +148,13 @@ Together with @ref file-formats-scene-importers "scene importers" derived from
 <th rowspan="2">Radiance HDR<br/>(`*.hdr`)</th>
 <td rowspan="2">`HdrImporter`</td>
 <td>@ref Trade::StbImageImporter "StbImageImporter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-StbImageImporter-behavior "none"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-primary">public&nbsp;domain</td>
 </tr>
 <tr>
 <td>@ref Trade::DevIlImageImporter "DevIlImageImporter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-DevIlImageImporter-behavior "none"</td>
 <td class="m-text-center m-danger">external</td>
 <td class="m-text-center m-warning">LGPLv2.1</td>
 </tr>
@@ -192,7 +192,7 @@ Together with @ref file-formats-scene-importers "scene importers" derived from
 </tr>
 <tr>
 <td>@ref Trade::DevIlImageImporter "DevIlImageImporter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-DevIlImageImporter-behavior "none"</td>
 <td class="m-text-center m-danger">external</td>
 <td class="m-text-center m-warning">LGPLv2.1</td>
 </tr>
@@ -218,7 +218,7 @@ Together with @ref file-formats-scene-importers "scene importers" derived from
 </tr>
 <tr>
 <td>@ref Trade::StbImageImporter "StbImageImporter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-StbImageImporter-behavior-png "none"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-primary">public&nbsp;domain</td>
 </tr>
@@ -256,13 +256,13 @@ Together with @ref file-formats-scene-importers "scene importers" derived from
 </tr>
 <tr>
 <td>@ref Trade::StbImageImporter "StbImageImporter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-StbImageImporter-behavior "none"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-primary">public&nbsp;domain</td>
 </tr>
 <tr>
 <td>@ref Trade::DevIlImageImporter "DevIlImageImporter"</td>
-<td class="m-text-center m-dim">unknown</td>
+<td class="m-text-center m-dim">@ref Trade-DevIlImageImporter-behavior "unknown"</td>
 <td class="m-text-center m-danger">external</td>
 <td class="m-text-center m-warning">LGPLv2.1</td>
 </tr>
@@ -308,7 +308,7 @@ Derived from @ref Trade::AbstractImageConverter.
 <th>Windows Bitmap (`*.bmp`)</th>
 <td>`BmpImageConverter`</td>
 <td>@ref Trade::StbImageConverter "StbImageConverter"</td>
-<td class="m-text-center m-dim">unknown</td>
+<td class="m-text-center m-dim">@ref Trade-StbImageConverter-behavior "unknown"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-primary">public&nbsp;domain</td>
 </tr>
@@ -334,7 +334,7 @@ Derived from @ref Trade::AbstractImageConverter.
 <th>Radiance HDR (`*.hdr`)</th>
 <td>`HdrImageConverter`</td>
 <td>@ref Trade::StbImageConverter "StbImageConverter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-StbImageConverter-behavior "none"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-primary">public&nbsp;domain</td>
 </tr>
@@ -392,7 +392,7 @@ Derived from @ref Trade::AbstractImageConverter.
 </tr>
 <tr>
 <td>@ref Trade::StbImageConverter "StbImageConverter"</td>
-<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
+<td class="m-text-center m-dim">@ref Trade-StbImageConverter-behavior "none"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-primary">public&nbsp;domain</td>
 </tr>
@@ -436,7 +436,7 @@ Together with @ref file-formats-image-importers "image importers" derived from
 <th>Autodesk FBX (`*.fbx`)</th>
 <td>`FbxImporter`</td>
 <td>@ref Trade::AssimpImporter "AssimpImporter"</td>
-<td class="m-text-center m-dim">unknown</td>
+<td class="m-text-center m-dim">@ref Trade-AssimpImporter-behavior "unknown"</td>
 <td class="m-text-center m-warning">bundleable</td>
 <td class="m-text-center m-success">BSD 3-clause</td>
 </tr>
@@ -468,7 +468,7 @@ Together with @ref file-formats-image-importers "image importers" derived from
 </tr>
 <tr>
 <td>@ref Trade::AssimpImporter "AssimpImporter"</td>
-<td class="m-text-center m-dim">unknown</td>
+<td class="m-text-center m-dim">@ref Trade-AssimpImporter-behavior "unknown"</td>
 <td class="m-text-center m-warning">bundleable</td>
 <td class="m-text-center m-success">BSD 3-clause</td>
 </tr>
@@ -522,7 +522,7 @@ Together with @ref file-formats-image-importers "image importers" derived from
 </tr>
 <tr>
 <td>@ref Trade::AssimpImporter "AssimpImporter"</td>
-<td class="m-text-center m-dim">unknown</td>
+<td class="m-text-center m-dim">@ref Trade-AssimpImporter-behavior "unknown"</td>
 <td class="m-text-center m-warning">bundleable</td>
 <td class="m-text-center m-success">BSD 3-clause</td>
 </tr>