Add note in output header for change in default CRISPRessoPooled

In the next release (2.3.0) the `--demultiplex_only_at_amplicons` will be the
default when running in mixed-mode. This is to allow for inexact alignments of
the reads and the amplicons to the genome. For more context, see this issue
pinellolab#276

CRISPResso2/CRISPRessoShared.py

@@ -1624,7 +1624,7 @@ def get_crispresso_header(description, header_str):
                 term_width) + "\n" + output_line
 
     output_line += '\n' + ('[CRISPResso version ' + __version__ + ']').center(term_width) + '\n' + (
-        '[Note that starting in version 2.3.0 FLASh and Trimmomatic will be replaced by fastp for read merging and trimming. Accordingly, the --flash_command and --trimmomatic_command parameters will be replaced with --fastp_command. Also, --trimmomatic_options_string will be replaced with --fastp_options_string.]').center(
+        '[Note that starting in version 2.3.0 FLASh and Trimmomatic will be replaced by fastp for read merging and trimming. Accordingly, the --flash_command and --trimmomatic_command parameters will be replaced with --fastp_command. Also, --trimmomatic_options_string will be replaced with --fastp_options_string.\n\nAlso in version 2.3.0, when running CRISPRessoPooled in mixed-mode (amplicon file and genome are provided) the default behavior will be as if the --demultiplex_only_at_amplicons parameter is provided. This change means that reads and amplicons do not need to align to the exact locations.]').center(
         term_width) + "\n" + ('[For support contact [email protected] or [email protected]]').center(term_width) + "\n"
 
     description_str = ""