more advanced workflows

src/SUMMARY.md

@@ -25,12 +25,13 @@
     - [Using named branches in jj](sharing-code/named-branches.md)
     - [Working with remotes, aka, GitHub](sharing-code/remotes.md)
     - [Responding to pull request feedback](sharing-code/updating-prs.md)
+    - [Updating trunk from upstream]()
+    - [Using jj with Gerrit]()
 
-- [More advanced workflows]()
-    - [Getting a bit philosophical]()
-    - [Workspaces]()
+- [More advanced workflows](advanced/more-advanced-workflows.md)
+    - [Working on all of your branches simultaneously](advanced/simultaneous-edits.md)
     - [Stacked PRs]()
-    - [Using jj with Gerrit]()
+    - [Workspaces]()
     - [Colocated Repositories]()
 
 - [Fixing Problems]()

src/advanced/more-advanced-workflows.md

@@ -0,0 +1,13 @@
+# More advanced workflows
+
+One of the best parts about using a version control system is the ability to
+share that code with other people. So far, we've been using jj entirely on our
+own machine, but it's time to explore how we can interface with tools that let
+us collaborate.
+
+Here's what we're going to learn:
+
+* Working on all your branches simultaneously
+* A pull request workflow called "Stacked PRs"
+* Workspaces that let you have multiple local checkouts
+* Using `git` and `jj` at the same time with colocated repositories