various: Spelling fixes

cc3200/README.md

docs/library/btree.rst

docs/library/machine.SD.rst

docs/library/machine.UART.rst

docs/library/uhashlib.rst

docs/library/utime.rst

docs/sphinx_selective_exclude/README.md

docs/sphinx_selective_exclude/modindex_exclude.py

esp8266/README.md

esp8266/machine_rtc.c

examples/conwaylife.py

examples/embedding/Makefile.upylib

examples/embedding/README.md

extmod/modlwip.c

extmod/modwebsocket.c

lib/timeutils/timeutils.c

lib/utils/stdout_helpers.c

py/asmthumb.c

py/builtinimport.c

py/compile.c