Avx2 deprecation pt2 (#3800)

* Initial draft of AVX2 deprecation notice. Also cleaned up the Clock Source section a bit.

* Added example to show whether processor has avx2.

* Minor tweaks

* Typo fix spotted by Ray

Co-authored-by: Ray Offiah <[email protected]>

* Verb agreement fix from Ray

Co-authored-by: Ray Offiah <[email protected]>

---------

Co-authored-by: Ray Offiah <[email protected]>

Author: ggray-cb

modules/install/pages/pre-install.adoc

@@ -4,14 +4,49 @@
 [abstract]
 {description}
 
-[tabs]
+## CPU Requirements
+
+Couchbase Server can run on x86 and ARM processors (including Apple Silicon processors). 
+This section explains the minimum requirements for of these platforms.
+
+### x86 Processors
+
+
+[#avx2-requirements]
+.deprecation notice
+[IMPORTANT]
+====
+The use of older x86 processors that do not implement the https://en.wikipedia.org/wiki/Advanced_Vector_Extensions#AVX2[Advanced Vector Extensions 2 (AVX2)] instruction set are deprecated in Couchbase Server 7.6.x.
+Future versions will require processors that have AVX2 support.
+This requirements is only for x86 processors--ARM processors have a separate set of vector instructions.
+
+The earliest processors that support AVX2 instructions include:
+
+* Intel 4th generation (Haswell) Core processors released in 2013.
+* Intel 11th generation (Tiger Lake) Celeron and Pentium processors released in 2020.
+* AMD Excavator processors released in 2015.
+
+Processors from these or later generations will be required to run Couchbase Server in the future.
+
+On Linux, you can tell if your processor has the AVX2 instructions by executing the following command:
+
+[source,bash]
+----
+grep -q -i 'avx2' /proc/cpuinfo && \
+     echo "Processor has AVX2" || echo "AVX2 not found"
+----
+
+If the command returns the text `Processor has AVX2`, your processor is supported in future Couchbase Server releases.
+If the command returns `AVX2 not found`, your processor does not have AVX2 instructions and will not be supported in future Couchbase Server versions.
 ====
-x86 Processors::
-+
---
+
+
+Couchbase Server has the following requirements when running on x86 processors.
+
+
 [cols="80,180,180"]
 |===
-| | Minimum Specifications* | Recommended Specifications**
+| | Minimum Specifications<<#note1,*>> | Recommended Specifications<<#note2,**>>
 
 | *CPU*
 | 2 GHz dual core x86_64 CPU supporting SSE4.2
@@ -39,14 +74,15 @@ a|
 
 Network file systems such as CIFS and NFS are not supported.
 |===
---
 
-ARM Processors::
-+
---
+### ARM Processors
+
+Couchbase Server has the following requirements when running on ARM-based platforms.
+
+
 [cols="80,180,180"]
 |===
-| | Minimum Specifications* | Recommended Specifications**
+| | Minimum Specifications<<#note1,*>> | Recommended Specifications<<#note2,**>>
 
 | *CPU*
 | 2 Ghz dual core 64bit ARM v8 CPU
@@ -66,12 +102,9 @@ a|
 
 Network file systems such as CIFS and NFS are not supported.
 |===
---
-====
-
-
 
-*_You can reduce the CPU and RAM resources below the Minimum Specifications for development and testing purposes.
+[#note1]
+^*^You can reduce the CPU and RAM resources below the Minimum Specifications for development and testing purposes.
 Resources can be as low as 1 GB of free RAM beyond operating system requirements, and a single CPU core.
 However, you must adhere to the Minimum Specifications for production._