Updated CI configurations and README that explained them (#436)

* Update config.yml
* Update README.markdown

.circleci/config.yml

@@ -1,10 +1,13 @@
 version: 2.1
 executors: #(1)
   exectr:
-    docker:
-      - image: dockerben/cpptemplate:latest
+      docker:
+      - image: cimg/base:edge-20.04
+    #docker:
+    #  - image: dockerben/cpptemplate:latest
     # example, maybe setup my own image later
     # https://thoughts-on-coding.com/2020/04/20/a-cpp-github-template-repository-utilizing-circleci-cmake-docker-and-doxygen/
+    # should look into Windows, Ubuntu, OSX executions in parallell with CircleCI ref https://circleci.com/docs/2.0/parallelism-faster-jobs/
 jobs:
   build:
     executor: exectr #(1)
@@ -13,4 +16,7 @@ jobs:
       - run: 
           name: build_and_run
           command: |
-            ./scripts/buildAndRunTests.sh
+            ./scripts/buildAndRunTests.sh
+      
+
+

README.markdown

@@ -33,6 +33,7 @@ LOGF(WARNING, "Printf-style syntax is also %s", "available");
   * [Testing](#testing)
   * [CMake Module](#cmake-module)
 * Overview of the [API description](#overview-api-description)
+* [Continuos_Integration](#continuos_integration)
 * [Performance](#performance)
 * [Feedback](#feedback)
 * [Say Thanks](#say-thanks)
@@ -491,6 +492,25 @@ G3log aims to keep all background logging to sinks with as little log overhead a
 The worst case latency is kept stable with no extreme peaks, in spite of any sudden extreme pressure.  I have a blog post regarding comparing worst case latency for g3log and other loggers which might be of interest.
 You can find it here: https://kjellkod.wordpress.com/2015/06/30/the-worlds-fastest-logger-vs-g3log/
 
+
+# <a name="continuos_integration">Continuos Integration</a>
+This repo has currently a few different CI setups. It might be that they are consolidated later. Currently it's trying out both github actions and circleCI. 
+For windows the repo is still relying on appveyor.  In case you want to look into change any of these setups the following files are the ones of interest. 
+```
+1. appveyor --> g3log/appveyor.yml
+2. circleCI --> g3log/.circleci/config.yml
+3. github actions --> g3log/.github/workflows/cpp.yml: calls a script that does all heavy lifting, leaving the yml barebone. Verbose test output
+4. github actions -->g3log/.github/workflows/cmake.yml: does all lifting with cmake commands, including test. Test output is just summary. 
+
+2. and 3. are currently relying on scripts/buildAndRunTests.sh
+
+Files that are obsolete but not yet deleted (due to testing)
+g3log/scripts/.travis-bootstrap-ubuntu.sh
+
+
+```
+
+
 # <a name="feedback">Feedback</a>
 If you like this logger (or not) it would be nice with some feedback. That way I can improve g3log and g2log and it is also nice to see if someone is using it.