nvs_flash: Fix typo in README.rst Merges https://github.com/espressif/esp-idf/pull/3216
nvs_flash: Fix typo in README.rst
Merges https://github.com/espressif/esp-idf/pull/3216

This should read "except for the new key-value pair" instead of
"expect for the new key-value pair".

Signed-off-by: Tim Nordell <24bc46b2aca1e8a3bd096ce3dcf529d81b3df255@nimbelink.com>

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf