Update web-sites-php-configure.md

The document refers to the maximum upload size, specifying it as "10 mb" in the text, and "10m" in the code sample. The correct info is "10m" (no B, no SPACE), so changed the text:

"2.Add configuration settings to the .user.ini file using the same syntax you would use in a php.ini file. For example, if you wanted to turn the display_errors setting on and set upload_max_filesize setting to 10 MB, " 

to say:

"2.Add configuration settings to the .user.ini file using the same syntax you would use in a php.ini file. For example, if you wanted to turn the display_errors setting on and set upload_max_filesize setting to 10M, "