[no-ci] Update README.md

Author: lemire

README.md

@@ -151,3 +151,16 @@ In this implementation, the hashing functions used is [murmurhash](github.com/tw
 
 Given the particular hashing scheme, it's best to be empirical about this. Note
 that estimating the FP rate will clear the Bloom filter.
+
+
+
+
+### Goroutine safety
+
+In general, it not safe to access
+the same filter using different goroutines--they are
+unsynchronized for performance. Should you want to access
+a filter from more than one goroutine, you should
+provide synchronization. Typically this is done by using channels (in Go style; so there is only ever one owner),
+or by using `sync.Mutex` to serialize operations. Exceptionally, you may access the same filter from different
+goroutines if you never modify the content of the filter.