update documentation

- update documentation for `writeAttribute()`
- add documentation for `exists()` (thx @ax3l)

Author: psychocoderHPC

src/include/splash/DataCollector.hpp

@@ -366,6 +366,7 @@ namespace splash
          * @param type Type information for data.
          * @param dataName Name of the dataset in group \p id to write attribute to.
          * If dataName is NULL, the attribute is written for the iteration group.
+         * If the path dataName does not yet exist, missing groups will be created.
          * @param attrName Name of the attribute.
          * @param buf Buffer to be written as attribute.
          */

src/include/splash/core/DCGroup.hpp

@@ -59,6 +59,12 @@ namespace splash
         H5Handle openCreate(H5Handle base, std::string path) throw (DCException);
         void close() throw (DCException);
 
+        /** Check if a Group or Dataset Within a Group exist
+         *
+         * @param base open file handle
+         * @param path to either a group or data set
+         * @return true if either a dataset or a group exists at path
+         */
         static bool exists(H5Handle base, std::string path);
         static void remove(H5Handle base, std::string path) throw (DCException);