Improvements to schema table.

- Schema table now has attribute links and is open by default.
- Attributes are in 4 columns.
- Fixed various documentation bugs made visible by this change.
- Removed distance equality constraint from xml_native_reader.cc

PiperOrigin-RevId: 517558035
Change-Id: Ibc7715587dd4e72253231bfd55bd037f0193b3fd

src/xml/xml_native_reader.cc

@@ -79,7 +79,7 @@ void ReadPluginConfigs(tinyxml2::XMLElement* elem, mjCPlugin* pp) {
 
 //---------------------------------- MJCF schema ---------------------------------------------------
 
-static const int nMJCF = 191;
+static const int nMJCF = 190;
 static const char* MJCF[nMJCF][mjXATTRNUM] = {
 {"mujoco", "!", "1", "model"},
 {"<"},
@@ -298,8 +298,6 @@ static const char* MJCF[nMJCF][mjXATTRNUM] = {
             "active", "solref", "solimp"},
         {"tendon", "*", "8", "name", "class", "tendon1", "tendon2", "polycoef",
             "active", "solref", "solimp"},
-        {"distance", "*", "8", "name", "class", "geom1", "geom2", "distance",
-            "active", "solref", "solimp"},
     {">"},
 
     {"tendon", "*", "0"},