Add `keg_only :versioned_formula`.

This is used to indicate a formula is a version of another formula.
This will be used to provide a consistent interface for older formulae
versions and replaces the use of `conflicts_with`.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/Versions.md b/docs/Versions.md
index 9e679db7d..bd3ef8a5f 100644
--- a/docs/Versions.md
+++ b/docs/Versions.md
@@ -11,6 +11,6 @@ Versioned formulae we include must meet the following standards:
 
 * Versioned formulae should differ in major/minor (not patch) versions from the current stable release. This is because patch versions indicate bug or security updates and we want to ensure you apply security updates.
 * Formulae that depend on versioned formulae must not depend on the same formulae at two different versions twice in their recursive dependencies. For example, if you depend on `openssl@1.0` and `foo`, and `foo` depends on `openssl` then you must instead use `openssl`.
-* Versioned formulae should strive to be linked at the same time as their non-versioned counterpart (without patching). If this is not possible, favour either `conflicts_with` or `keg_only` depending on whether users expect to have multiple versions installed at once or not.
+* Versioned formulae should only be linkable at the same time as their non-versioned counterpart if the upstream project provides support for e.g. suffixed binaries. If this is not possible, use `keg_only :versioned_formula` to allow users to have multiple versions installed at once.
 
 You should create your own [tap](https://github.com/Homebrew/brew/blob/master/docs/How-to-Create-and-Maintain-a-Tap.md) for formulae you or your organisation wishes to control the versioning of or those that do not meet the above standards.