Update doxygen documentation for cirbuf

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INPUT = linux/source/drivers/elphel linux/source/drivers/ata/ahci_elphel.c linux/source/drivers/clk/clk-si5338.c linux/source/drivers/misc/ltc3589.c linux/source/drivers/misc/vsc330x.c linux/source/drivers/mmc/host/sdhci.c linux/source/drivers/mmc/host/sdhci.h linux/source/drivers/mtd/nand/nand_base.c linux/source/drivers/mtd/nand/nand.h linux/source/drivers/mtd/nand/nandchip-micron.c linux/source/drivers/mtd/nand/pl35x-nand.c linux/source/include/elphel linux/source/include/linux/i2c/ltc3589.h

INPUT_ENCODING = UTF-8

FILE_PATTERNS = *.h *.cpp *.md

FILE_PATTERNS = *.h *.c *.cpp *.md

RECURSIVE = YES

EXCLUDE = src/logos.cpp src/lodepng.cpp

EXCLUDE_SYMLINKS = NO