Add API usage documentation and restructure existing content

03.usage/03.api/00.overview/docs.md

@@ -0,0 +1,59 @@
+---
+title: API Client Usage
+taxonomy:
+    category: docs
+---
+
+## API Client Usage
+
+The rest API is using JWT TLS and is served by default on port 10005 by the replication-manager monitor/
+
+Credentials can be customized by setting your own user and password in configuration file.  
+
+```
+api-port ="10005"
+api-credential = "admin:repman"
+```
+
+At startup of the monitor, X509 certificates are loaded from the replication-manager share directory or from keys defined from config files to ensure TLS https secure communication.
+
+Replace those files with your own certificate signed or self signed to make sure your deployment is secured.
+
+```
+# Key considerations for algorithm "RSA" ≥ 2048-bit
+openssl genrsa -out server.key 2048
+
+# Key considerations for algorithm "ECDSA" ≥ secp384r1
+# List ECDSA the supported curves (openssl ecparam -list_curves)
+openssl ecparam -genkey -name secp384r1 -out server.key
+openssl req -new -x509 -sha256 -key server.key -out server.crt -days 3650
+```
+
+At startup **replication-manager** monitor will generate in memory extra self-signed RSA certificate to ensure later token encryption exchange for JWT.
+
+# Calling API via the client
+
+API can be called via command line client to simplify curl syntax with JWT token.
+
+```
+./replication-manager-cli api  --url="https://127.0.0.1:10005/api/clusters/ux_dck_zpool_loop/servers/actions/add/192.168.1.73/3306"   --cluster="ux_dck_zpool_loop"
+```
+
+# Calling API via curl or wget
+
+TOKEN=$(curl -s -k -X POST -H 'Accept: application/json' -H 'Content-Type: application/json' --data '{"username":"admin","password":"repman"}' https://demo.signal18.io/api/login | jq  -r '.token')
+
+or without json response  
+
+TOKEN=$(curl -s -k -X POST -H 'Accept: text/html' -H 'Content-Type: application/json' --data '{"username":"admin","password":"repman"}' https://127.0.0.1:10005/api/login)
+
+
+follow by your request:
+
+curl -k -H 'Accept: application/json' -H "Authorization: Bearer ${TOKEN}" https://demo.signal18.io/api/clusters
+
+Or via wget
+
+TOKEN=$(wget  -qO- --no-check-certificate --post-data '{"username":"admin","password":"repman"}' --header 'Accept: text/html' --header 'Content-Type: application/json'  https://127.0.0.1:10005/api/login)
+
+wget -qO- --no-check-certificate --header 'Accept: application/json' --header "Authorization: Bearer ${TOKEN}"  https://127.0.0.1:10005/api/clusters