Updated doxygen comment. SparseMatrix class no longe resembles eckit:… #479

Job	Run time
ci (Release, linux gnu-10)	14m 56s
ci (Release, linux gnu-10)	14m 56s
ci (Release, linux gnu-12)	15m 31s
ci (Release, linux gnu-12)	15m 31s
ci (Release, linux gnu-7)	12m 52s
ci (Release, linux gnu-7)	12m 52s
ci (Release, linux clang-12)	12m 43s
ci (Release, linux clang-12)	12m 43s
ci (Release, linux intel)	12m 25s
ci (Release, linux intel)	12m 25s
ci (Release, linux intel-classic)	17m 1s
ci (Release, linux intel-classic)	17m 1s
ci (Release, macos)	16m 24s
ci (Release, macos)	16m 24s
ci (Debug, linux gnu-10)	18m 31s
ci (Debug, linux gnu-10)	18m 31s
ci (Debug, linux gnu-12)	15m 41s
ci (Debug, linux gnu-12)	15m 41s
ci (Debug, linux gnu-7)	14m 1s
ci (Debug, linux gnu-7)	14m 1s
ci (Debug, linux clang-12)	13m 58s
ci (Debug, linux clang-12)	13m 58s
ci (Debug, linux intel)	11m 53s
ci (Debug, linux intel)	12m 36s
ci (Debug, linux intel-classic)	15m 48s
ci (Debug, linux intel-classic)	15m 48s
ci (Debug, macos)	16m 19s
ci (Debug, macos)	16m 19s
	6h 56m 49s

Provide feedback