Update CHANGELOG.md to make clear that the regularisation can be complex but snr real in obsFilt.m

CHANGELOG.md

@@ -40,8 +40,8 @@
 \* Parallelise the for-loops in `obsFiltEst()`. While execution may be slower for a small number of sources and receiver positions, the overall execution time will not increase significantly due to the functions' generally fast performance.\
 \* Parallelise on of the for-loops in `obsFiltTD()`. While execution may be slower for a small number of sources and receiver positions, the overall execution time will not increase significantly due to the functions' generally fast performance.\
 \* Update `obsFilt()` to return the condition of the perturbed power spectral density matrix.\
-\* Update `obsFilt()` to allow a matrix of regularisation factors to be provided (it must be square and its dimensions must be equal to the monitoring microphones' power spectral density matrix).\
-\* Update `obsFilt()` to allow a matrix of SNR values to be provided (it must be square and its dimensions must be equal to the monitoring microphones' power spectral density matrix).\
+\* Update `obsFilt()` to allow a matrix of *complex* regularisation factors to be provided (it must be square and its dimensions must be equal to the monitoring microphones' power spectral density matrix).\
+\* Update `obsFilt()` to allow a matrix of *real* SNR values to be provided (it must be square and its dimensions must be equal to the monitoring microphones' power spectral density matrix).\
 \* Rename the following functions (this **breaks** backward compatibility):
   - `obsFiltTD()` to `obsFiltTd()`
   - `obsFiltEstTD()` to `obsFiltEstTd()`