Docs: Add a FAQ

This answers some questions, which were repeatly asked in Discord.

README.md

@@ -318,6 +318,8 @@ The best way to get started is probably to go through
 [Git comparison](docs/git-comparison.md), which includes a table of
 `jj` vs. `git` commands.
 
+After your familiar with Jujutsu, the [FAQ](docs/FAQ.md) may help.
+
 ## Related work
 
 There are several tools trying to solve similar problems as Jujutsu. See

docs/FAQ.md

@@ -0,0 +1,58 @@
+# Frequently asked questions
+
+### Why does my branch not move to the new commit after `jj new/commit`?
+
+Jujutsu's branches are akin to Git Tags, they always point to a single commit.
+To move them, use `jj branch set`. 
+
+### Where is my commit, why is it not visible in `jj log`? 
+
+If you don't find it with `jj log -r 'all()', it may be time to set the config
+`revsets.log` to something more matching.
+
+See [revsets], [templates] and [config] for guidance.
+
+### Is there something like `git rebase`? 
+
+For now its recommended to rebase the commit individually with 
+`jj rebase -s $changeid -d $new-parent`.
+
+In the future there may be a `histedit` command, which alleviates that.
+
+
+### How do I partially add changes from a file? 
+
+With Jujutsu you never partially add hunks, as your always amending the 
+`@` commit. You need to split it, as the `@` may already be complete.
+
+This is easy doable with `jj split your-file`
+
+
+### How can I keep my scratch files in the repository?
+
+You can keep your notes and other scratch files in the repository, if you add 
+a wildcard pattern to the `gitignore`. Something like `*.scratch` or 
+`*.scratchpad` should do, after that rename the files you want to keep around
+to match the pattern.
+
+### How can I keep my Git-like workflow?
+
+In contrast to Git, we suggest keeping the branch pointing at the first commit.
+This is so you can keep adding child commits to the branch, to create a new commit, 
+use `jj checkout/new heads(:your-branch)`.
+
+To see your current work, use `jj log -r your-branch:` which means children of
+`your branch`.
+
+
+### How can I keep local changes around, but not use them for Pull Requests? 
+
+In general you can create a local commit, which incorporates your changes and 
+then rebase all your open work on it. Before creating a PR, remove the 
+change from the branches history with e.g `jj rebase -s $change-id -d main`. 
+
+
+
+[config]: ./config.md
+[revsets]: ./revsets.md
+[templates]: ./templates.md