docs: update again

Author: G-Rath

tools/apitester/README.md

@@ -18,12 +18,6 @@ Each cassette is a YAML file in `testdata/cassettes` that stores an array of
 Of these, the tool only uses the `request` field, and the `response` field will
 be automatically removed as part of running tool.
 
-The `request` in each interaction for a cassette is replayed and the response
-body captured as a snapshot for the particular cassette using
-[`go-snaps`](https://github.com/gkampitakis/go-snaps) - subsequent runs will
-compare the response body with the existing snapshot and show a diff of any
-differences.
-
 ## Usage
 
 As this tool uses packages intended for being used in tests, it must be run
@@ -33,8 +27,20 @@ using `go test`:
 go test ./...
 ```
 
-You can regenerate snapshots by setting `UPDATE_SNAPS=true` when running tests:
+This replays each recorded `request` in `testdata/cassettes` and capture the
+response body as a snapshot using
+[`go-snaps`](https://github.com/gkampitakis/go-snaps); subsequent runs will
+compare the response body with the existing snapshot and report any differences.
+
+By default, any differences in existing snapshots will be considered a failure -
+you can have the snapshots updated instead by setting `UPDATE_SNAPS=true`:
 
 ```shell
 UPDATE_SNAPS=true go test ./...
 ```
+
+Before the test suite is actually run, the cassettes will be "cleaned" so that
+
+- the `body` of each `request` will be formatted as a multi-line string, to make
+  it easier to understand what the query parameters are
+- the `response` is property is not present, to reduce the size of each cassette