docs: Document Python TLS requirements (#12276)

* 🔧 Add simple test script

* 📝 Add documentation

* 🔧 It works, use it

* 🔧 Make the linter happy

* 🔧 Check on bootstrap

* Trivial copyediting

s/operation system/operating system/

docs/development/build-instructions-linux.md

@@ -7,6 +7,19 @@ Follow the guidelines below for building Electron on Linux.
 * At least 25GB disk space and 8GB RAM.
 * Python 2.7.x. Some distributions like CentOS 6.x still use Python 2.6.x
   so you may need to check your Python version with `python -V`.
+
+  Please also ensure that your system and Python version support at least TLS 1.2.
+  For a quick test, run the following script:
+
+  ```sh
+  $ python ./script/check-tls.py
+  ```
+
+  If the script returns that your configuration is using an outdated security
+  protocol, use your system's package manager to update Python to the latest
+  version in the 2.7.x branch. Alternatively, visit https://www.python.org/downloads/
+  for detailed instructions.
+
 * Node.js. There are various ways to install Node. You can download
   source code from [nodejs.org](https://nodejs.org) and compile it.
   Doing so permits installing Node on your own home directory as a standard user.