[TD] uniform wording

in other/existing elements of line width we speak of "width", so do the same for line groups

src/Mod/TechDraw/Gui/DlgPrefsTechDrawAnnotation.ui

@@ -696,7 +696,7 @@
            <string>Line group used to set line widths</string>
           </property>
           <property name="text">
-           <string>Line Group</string>
+           <string>Line Width Group</string>
           </property>
          </widget>
         </item>

src/Mod/TechDraw/Gui/DlgPrefsTechDrawAnnotationImp.cpp

@@ -156,7 +156,7 @@ void DlgPrefsTechDrawAnnotationImp::onLineGroupChanged(int index)
     }
     // format the tooltip
     std::stringstream TooltipText;
-    TooltipText << lgNames.at(0).substr(1) << " defines these line thicknesses:\n"
+    TooltipText << lgNames.at(0).substr(1) << " defines these line widths:\n"
         << "thin: " << lgNames.at(1) << "\n"
         << "graphic: " << lgNames.at(2) << "\n"
         << "thick: " << lgNames.at(3);