[Docs] Add docs for trampolining

🎉

1 files changed, 18 insertions, 0 deletions

diff --git a/man/bundle.ronn b/man/bundle.ronn
index f2b1daa08f..065cfd4490 100644
--- a/man/bundle.ronn
+++ b/man/bundle.ronn
@@ -91,6 +91,24 @@ When running a command that isn't listed in PRIMARY COMMANDS or UTILITIES,
 Bundler will try to find an executable on your path named `bundler-<command>`
 and execute it, passing down any extra arguments to it.
 
+## BUNDLER TRAMPOLINING
+
+Bundler includes a feature called trampolining, designed to allow a single
+developer to work on multiple projects, each on different Bundler versions.
+The trampoline will infer the correct version of Bundler to use for each project
+and load that version instead of the version directly invoked (which is almost
+always the newest version installed locally).
+
+Bundler by default will use the Bundler version in the current directory to
+determine the version to trampoline to, reading from the `BUNDLED WITH` section.
+However, if the `BUNDLER_VERSION` environment variable is set, that version will
+override the lockfile inference and can be used in directories without a
+lockfile.
+
+Until the target version is Bundler 2 or later, `BUNDLE_ENABLE_TRAMPOLINE` must
+be set for the trampoline to be used. Additionally, `BUNDLE_DISABLE_POSTIT` can
+be set to completely disable the trampoline.
+
 ## OBSOLETE
 
 These commands are obsolete and should no longer be used