Do not expose plugin_slot.

PiperOrigin-RevId: 683215401
Change-Id: Ic64f7221ed83ca3b0c8cca16eb680ea67c67b564

doc/APIreference/functions.rst

@@ -1516,7 +1516,7 @@ mjs_activatePlugin
 
 .. mujoco-include:: mjs_activatePlugin
 
-Activate plugin, return slot number.
+Activate plugin.
 
 .. _Errorandmemory:
 

doc/includes/references.h

@@ -1739,9 +1739,8 @@ typedef struct mjsOrientation_ {   // alternative orientation specifiers
 } mjsOrientation;
 typedef struct mjsPlugin_ {        // plugin specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
+  mjString* name;                  // instance name
   mjString* plugin_name;           // plugin name
-  int plugin_slot;                 // global registered slot number of the plugin
   mjtByte active;                  // is the plugin active
   mjString* info;                  // message appended to compiler errors
 } mjsPlugin;
@@ -3171,7 +3170,7 @@ int mj_setLengthRange(mjModel* m, mjData* d, int index,
 mjSpec* mj_makeSpec(void);
 mjSpec* mj_copySpec(const mjSpec* s);
 void mj_deleteSpec(mjSpec* s);
-int mjs_activatePlugin(mjSpec* s, const char* name);
+void mjs_activatePlugin(mjSpec* s, const char* name);
 void mj_printFormattedModel(const mjModel* m, const char* filename, const char* float_format);
 void mj_printModel(const mjModel* m, const char* filename);
 void mj_printFormattedData(const mjModel* m, mjData* d, const char* filename,