README.md: remove outdated information

There is some outdated information in the README.md files of
hello-stk and imsi-change.

Related: OS#6069

hello-stk/README.md

@@ -1,8 +1,4 @@
 # Hello World SIM Toolkit Program
 
 This is the source code to a very simple *Hello World* Java SIM Toolkit
-application.  You typically install it using the tools from the
-<http://git.osmocom.org/sim/sim-tools/> repository.
-
-For more information see
-<https://osmocom.org/projects/cellular-infrastructure/wiki/Shadysimpy>
+application.

imsi-change/README.md

@@ -4,23 +4,6 @@ Display and change the IMSI of the SIM. This is a standalone version of a debug
 feature in the more complex IMSI Pseudonymization applet. To be used as example
 code to build other applets.
 
-### How to flash
-
-```
-$ cp .sim-keys.example .sim-keys
-$ nvim .sim-keys # adjust KIC1, KID1
-$ make flash
-```
-
-Before flashing a second time, remove the sim applet:
-
-```
-$ make remove
-```
-
 ### Related
 
 * [IMSI Pseudonymization](https://osmocom.org/projects/imsi-pseudo/wiki)
-* [Shadysimply in Osmocom wiki](https://osmocom.org/projects/cellular-infrastructure/wiki/Shadysimpy)
-
-