Add very brief context about MongoDB and Redis relicensing

dosp-survey.ltx

@@ -456,10 +456,16 @@ a specific version, and its Change License is GPLv2.
 The Linux Foundation noted
 (\otsurl{https://www.linuxfoundation.org/blog/how-open-source-foundations-protect-the-licensing-integrity-of-open-source-projects})
 that several prominent projects switched away from open-source
-licenses from 2018 to 2023.  Not all of these adopted DOSP licenses,
-but those that did so adopted BUSL.  These included CockroachDB,
-Couchbase, Terraform, and ArangoDB.  The most prominent of these BUSL
-adopters was HashiCorp, which wrote
+licenses from 2018 to 2023.  Not all of these adopted DOSP licenses\footnote{The
+trend identified by the Linux Foundation began in late 2018, with two
+major database projects, Redis and MongoDB, adopting the Server-Side
+Public License (SSPL).  SSPL was proposed as an Open Source license,
+but was not ultimately accepted as Open Source by OSI's license review
+process. Some proponents of this license continue to argue that it
+meets criteria to be considered a form of free and open source
+licensing.}, but those that did so adopted BUSL.  These included
+CockroachDB, Couchbase, Terraform, and ArangoDB.  The most prominent
+of these BUSL adopters was HashiCorp, which wrote
 
 \begin{quote}
   BSL 1.1 is a source-available license that allows copying,
@@ -486,11 +492,13 @@ other companies from competing directly with the developers' hosted
 database services, and that they doubted whether an Open Source
 license would manage to accomplish this.\footnote{It's interesting to
   note that the majority of the projects we've identified that
-  relicensed under BUSL are database systems.  It's possible that
+  relicensed under BUSL are database systems. It's possible that
   there was a degree of ``social contagion'' as database developers
   observed several of their peers relicensing away from Open Source at
   roughly the same time, either to BUSL or to other licenses that
-  restrict licensees from operating commercial services.}
+  restrict licensees from operating commercial services. As noted
+  above, database developers were also responsible for several other
+  relicensing decisions starting in 2018.}
 
 By default, BUSL prohibits uses in ``production'' before the Change
 Date.  Licensors using the bare BUSL would thus expect commercial
@@ -989,6 +997,10 @@ proprietary-licensing scheme with proprietary and A/GPL options.
     % 
     % I haven't managed to find out whether it's correct that AWS was
     % offering MongoDB-as-a-service before the relicensing in 2018.
+    %
+    % I put in a brief reference to MongoDB's relicensing above without
+    % entering into the question of the rationale or what AWS's
+    % competitive offering might have been.
 
   \item \textbf{Effects on outside contributions.}