Update heatshrink_common.h filename in README.md to reflect rename.
Update heatshrink_common.h filename in README.md to reflect rename.

atomicobject/heatshrink,senyor/heatshrink,atomicobject/heatshrink,jordandcarter/heatshrink,unixdj/heatshrink-c,silentbicycle/heatshrink,jordandcarter/heatshrink,silentbicycle/heatshrink,senyor/heatshrink