Added an entry for linux-meta and linux-signed

docs/reference/glossary.md

@@ -18,5 +18,27 @@ ABI
   ABI remains unchanged.
 
 linux-meta
-  Define linux-meta.
+  Refers to a set of meta-packages in Linux distributions like Ubuntu. These meta-packages do not  
+  contain the kernel binaries or source code themselves but instead define dependencies that point  
+  to the latest kernel packages. By installing a linux-meta package (e.g. linux-generic), users can  
+  ensure they always receive the latest version of a specific kernel series through updates. In  
+  the kernel development and {term}`SRU` lifecycle, linux-meta acts as a bridge between the release  
+  of new kernel versions and the package manager. When a new kernel version is releasedand marked  
+  stable, the linux-meta package is updated to reference the new version, allowing automatic upgrades.  
+
+linux-signed 
+  Refers to kernel packages that are cryptographically signed to ensure their integrity and  
+  authenticity. These signatures are crucial for secure boot environments, as they enable the  
+  system firmware to verify that the kernel has not been tampered with and is from a trusted  
+  source. In the kernel {term}`SRU` lifecycle, linux-signed is created after the corresponding  
+  unsigned kernel (e.g. linux-image-unsigned-6.8.0-50-generic) has been built. The signing  
+  process is part of the release pipeline, ensuring compliance with secure boot requirements  
+  and enhancing security in the kernel deployment process. This package works in tandem with  
+  the linux-meta package to deliver signed kernel updates.
+
+SRU
+  Stands for Stable Release Update, a process in distributions like Ubuntu used to provide important 
+  updates to packages, including kernel packages, after the release of a stable version. SRUs deliver 
+  fixes for critical bugs, security vulnerabilities, and hardware enablement while ensuring the stability 
+  of the system.
 ```