Same filename in this branch
  1. 5.x sites/all/README.txt
  2. 5.x developer/database/README.txt
Same filename and directory in other branches
  1. 6.x sites/all/README.txt
This directory should be used to place downloaded and custom modules
and themes which are common to all sites. This will allow you to
more easily update Drupal core files. These modules and themes should
be placed in subdirectories called modules and themes as follows:

  sites/all/modules
  sites/all/themes

File

sites/all/README.txt
View source 
  1. 

  2. This directory should be used to place downloaded and custom modules

  3. and themes which are common to all sites. This will allow you to

  4. more easily update Drupal core files. These modules and themes should

  5. be placed in subdirectories called modules and themes as follows:

  6. 

  7.   sites/all/modules

  8.   sites/all/themes