Fix a bunch of links

CONTRIBUTING.md

@@ -257,9 +257,6 @@ There are some great (but limited) options for anyone lacking the ability to do
 
 - [REPL.it](https://replit.com/languages/rust) - This online IDE includes a low-powered machine to compile Rust on, but provides _real-time collaboration_ where multiple users can follow-the-leader and edit simultaneously.
   It also features github integrations to save and share progress.
-- [Substrate Playground](https://docs.substrate.io/playground/) - This is a Parity hosted very powerful build machine that anyone can access using a pre-compiled docker image of the base [substrate node template](https://github.com/substrate-developer-hub/substrate-node-template) to build on top of in an online VSCode-like IDE.
-  The session is limited to 2 hours per user, before all data is cleared. There is no simple way to capture your work though, so this is only to be used in simple examples of substrate to iterate very quickly.
-  _Note that it is unclear if 50+ students can access this at the same time, thus please let the TAs know if you plan to use this first!_
 
 ### Conceptual workshops and activities
 

previous_syllabus/0-Miscellaneous/0-Security/appsec_lecture-material.md

@@ -547,7 +547,7 @@ In summary, **The adaptation, communication and enforcement of coding are essent
 3.  CSSLP Certified Secure Software Lifecycle Professional All-in-One Exam Guide, Third Edition, by Wm. Arthur Conklin, Daniel Paul Shoemaker: <https://www.mheducation.co.uk/csslp-certified-secure-software-lifecycle-professional-all-in-one-exam-guide-third-edition-9781264258208-emea> <!-- markdown-link-check-disable-line -->
 
 4.  (ISC)2 CISSP Certified Information Systems Security Professional Official Study Guide, by Mike Chapple, James Michael Stewart, Darril Gibson, David Seidl: <https://www.wiley.com/en-gb/(ISC)2+CISSP+Certified+Information+Systems+Security+Professional+Official+Study+Guide+&+Practice+Tests+Bundle,+3rd+Edition-p-9781119790020> <!-- markdown-link-check-disable-line -->
-5.  CISSP for Dummies, Lawrence C. Miller, Peter H. Gregory: <https://www.wiley.com/en-gb/CISSP+For+Dummies,+7th+Edition-p-9781119806820>
+5.  CISSP for Dummies, Lawrence C. Miller, Peter H. Gregory: <https://www.wiley.com/en-us/CISSP+For+Dummies%2C+8th+Edition-p-9781394261789>
 
 6.  CISM Certified Information Security Manager Study Guide, by Mike Chapple: <https://www.wiley.com/en-gb/CISM+Certified+Information+Security+Manager+Study+Guide-p-9781119801948>
 7.  Secure Rust Guidelines: <https://anssi-fr.github.io/rust-guide>

syllabus/1-Cryptography/README.md

@@ -29,7 +29,7 @@ They should not zone-out of class to complete this during class time, they shoul
 1. [1-Intro](1-Intro-slides.md)
 1. [2-Addresses](2-Addresses-slides.md)
    - 🪄 [`subkey` demo](./materials/subkey-demo.md)
-1. 💻 [Many time pad](many-time-pad.md) activity
+1. 💻 [Many time pad](./materials/many-time-pad.md) activity
 
 Release:
 1. `p2_addresses` assignment problem

syllabus/6-Polkadot-SDK/Substrate/README.md

@@ -31,13 +31,13 @@ Ensure the `main` branch is write protected, by required a PR first`- no one sho
 #### Morning
 
 1. [Introduction](./1-Intro-to-Substrate-slides.md) (60m)
-1. [Wasm Meta Protocol](./2-Wasm-Meta-Protocol-Slides.md) (90m)
+1. [Wasm Meta Protocol](./2-Wasm-Meta-Protocol-slides.md) (90m)
 <!-- FIXME where is this? -->
 1. Activity: Finding Runtime APIs and Host Functions in Substrate
 
 #### Afternoon
 
-1. [Show Me The Code](./9-Substrate-In-The-Code-slides.md) (60m)
+1. Show Me The Code (60m)
 1. [Substrate Interactions](./9-Substrate-Interactions-slides.md) (60m)
 1. FRAMELess Assignment (60m)
 
@@ -47,7 +47,7 @@ Ensure the `main` branch is write protected, by required a PR first`- no one sho
 
 1. [Transaction Pool](./4-Transaction-Pool-slides.md) (60m)
 1. [SCALE](./9-SCALE-slides.md) (60m)
-1. [Substrate and FRAME Tips and Tricks](./9-Substrate-FRAME-Tips-Tricks-Slides.md)
+1. [Substrate and FRAME Tips and Tricks](./9-Substrate-FRAME-Tips-Tricks-slides.md)
 
 #### Afternoon