docs: add FAQ for why to use new-then-amend over edit

cli/src/commands/edit.rs

@@ -26,6 +26,8 @@ use crate::ui::Ui;
 /// Note: it is generally recommended to instead to use `jj new` and `jj
 /// squash`. Creating a new revision enables being more intentional with respect
 /// to the existing revision.
+///
+/// For more information, see https://github.com/martinvonz/jj/blob/main/docs/FAQ.md#how-do-i-resume-working-on-an-existing-change
 #[derive(clap::Args, Clone, Debug)]
 pub(crate) struct EditArgs {
     /// The commit to edit

cli/tests/cli-reference@.md.snap

@@ -711,6 +711,8 @@ Sets the specified revision as the working-copy revision
 
 Note: it is generally recommended to instead to use `jj new` and `jj squash`. Creating a new revision enables being more intentional with respect to the existing revision.
 
+For more information, see https://github.com/martinvonz/jj/blob/main/docs/FAQ.md#how-do-i-resume-working-on-an-existing-change
+
 **Usage:** `jj edit <REVISION>`
 
 ###### **Arguments:**

docs/FAQ.md

@@ -137,6 +137,17 @@ commit, then run `jj restore --from Y --to @-` to restore the parent commit
 to the old state, and `jj restore --from X` to restore the new working-copy
 commit to the new state.
 
+### How do I resume working on an existing change?
+
+There are two ways to resume working on an earlier change: `jj new` then `jj squash`,
+and `jj edit`. The first is generally recommended over the second because at this
+point, your earlier change could have developed a conflict. In that case`jj edit`
+would restore the state with plain-text conflict annotations. Editing those
+annotations incorrectly or by accident can lead to undesired output from conflict
+resolution. To avoid this, you use `jj new <rev>` to create a change based on your
+earlier revision, make your edits, then use `jj squash`. Your earlier revision will
+now be updated with the new edits.
+
 ### How do I deal with divergent changes ('??' after the [change ID])?
 
 A [divergent change][glossary_divergent_change] represents a change that has two