PG-1345 Release notes 15.12 (#730)

PG-1345 Release notes 15.12

modified:   .github/workflows/main.yml
        deleted:    docs/how-to.md
        new file:   docs/release-notes-v15.12.md
        modified:   docs/release-notes.md
        modified:   mkdocs-base.yml
        modified:   mkdocs-pdf.yml
        modified:   requirements.txt
        modified:   variables.yml



Updated release highlights list
Added deprecation label to meta packages

Signed-off-by: Anastasia Alexadrova <anastasia.alexandrova@percona.com>

---------

Signed-off-by: Anastasia Alexadrova <anastasia.alexandrova@percona.com>

Author: nastena1606

.github/workflows/main.yml

@@ -12,12 +12,12 @@ jobs:
     steps: 
       #Pull the latest changes
       - name: Chekout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
-          fetch-depth: 0
+          fetch-depth: 0 # fetch all commits/branches
       #Prepare the env
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
         with:
           python-version: '3.x'
 
@@ -46,7 +46,7 @@ jobs:
       - name: Deploy docs
         run: |
           mike deploy 15 -b publish -p
-          mike retitle 15 "15.10" -b publish -p
+          mike retitle 15 "15.12" -b publish -p
 
 # - name: Install Node.js 14.x
 #        uses: percona-platform/setup-node@v2

docs/apt.md

@@ -43,7 +43,7 @@ Run all the commands in the following sections as root or using the `sudo` comma
 
 ### Install packages
 
-=== "Install using meta-package"
+=== "Install using meta-package (deprecated)"
 
     The [meta package](repo-overview.md#percona-ppg-server){:target=”_blank”} enables you to install several components of the distribution in one go.