Move GsweError and GSWE_ERROR documentation to .c file

This is to hide documentation details from installed .h files

src/swe-glib.c

@@ -34,6 +34,32 @@
  * objects, but on the library as a whole, including global tables.
  */
 
+/**
+ * GsweError:
+ * @GSWE_ERROR_SUCCESS: No error
+ * @GSWE_ERROR_SWE_NONFATAL: Non-fatal Swiss Ephemeris library error
+ * @GSWE_ERROR_SWE_FATAL: Fatal Swiss Ephemeris library error
+ * @GSWE_ERROR_INVALID_DATE: The specified Gregorian date is invalid
+ * @GSWE_ERROR_INVALID_TIME: The specified time is invalid
+ * @GSWE_ERROR_NO_VALID_VALUE: the #GsweTimestamp object holds no valid values
+ * @GSWE_ERROR_UNKNOWN_HSYS: the requested house system is unknown
+ * @GSWE_ERROR_UNKNOWN_SIGN: an invalid zodiac sign would have been returned
+ * @GSWE_ERROR_UNKNOWN_PLANET: the referenced planet was not added with
+ *                             gswe_moment_add_planet()
+ * @GSWE_ERROR_UNKNOWN_ANTISCION_AXIS: the given axis is unknown to SWE-GLib
+ * @GSWE_ERROR_UNKNOWN_ASPECT: the given aspect is unknown to SWE-GLib
+ *
+ * Error codes returned by the SWE-GLib functions.
+ */
+
+/**
+ * GSWE_ERROR:
+ *
+ * Error domain for SWE-GLib in general. Since 2.0, all errors generated by
+ * SWE-GLib functions are from this domain. See #GError for more information on
+ * error domains.
+ */
+
 gboolean gswe_initialized = FALSE;
 gchar *gswe_ephe_path = NULL;
 GHashTable *gswe_planet_info_table;