fix `space` character in README

[DennyDai]

The spaces used in the docker run command may look the same, but they are actually different characters. While a regular space is represented by the ASCII character 0x20, the command provided in the current README.md is using a non-breaking space (U+00A0 or 0xC2 0xA0 in UTF-8). Some shells treat docker[non-breaking space]run as a single word, causing the command to fail.

For references: https://www.scivision.dev/hex-code-c2a0-non-breaking-space-markdown/ https://community.notepad-plus-plus.org/topic/19862/replace-non-breaking-space-utf-8-c2-a0 https://news.ycombinator.com/item?id=27896856

Before Fix:

$ docker run -v ${PWD}:/DATA -w /DATA -i pinellolab/crispresso2 CRISPResso -h

docker run: command not found

After the fix:

$ docker run -v ${PWD}:/DATA -w /DATA -i pinellolab/crispresso2 CRISPResso -h

                               ~~~CRISPResso 2~~~                               
        -Analysis of genome editing outcomes from deep sequencing data-         

                                        _                                       
                                       '  )                                     
                                       .-'                                      
                                      (____                                     
                                   C)|     \                                    
                                     \     /                                    
                                      \___/                                     

                          [CRISPResso version 2.2.14]         
...