Update README for portable version.

README.md

@@ -18,6 +18,17 @@ Please note that due to a compatibility issue with the Chocolatey shims, running
 
 `mousejiggler --shimgen-log`
 
+Portable Version
+----------------
+
+A portable version of Mouse Jiggler (i.e., one which does not require the .NET 5 runtime, and so can be installed on locked-down corporate machines that don't have it installed) is available on the releases page, as MouseJiggler-portable.zip. Just unzip and go.
+
+**DO NOT USE THIS VERSION IF YOU HAVE ANY OTHER ALTERNATIVE.**
+
+Let me put it to you this way. _Standard_ Mouse Jiggler, at the time of writing, is a single executable a mite under 1 MB in size. _Portable_ Mouse Jiggler is a folder of executables summing to approximately **83 MB**, for one of the most trivial applications imaginable, after all the assorted trimming-and-compressing magic is done. It's a bloated behemoth. If there is _any_ possibility that you will _ever_ run any other app that uses the .NET 5 runtime, you are much better off installing that and the regular version.
+
+The only reason this exists is for those poor sods whose IT department makes it impossible to do that, and may their deities have mercy on their souls.
+
 Operation
 =========