add more docs

common/docs/knowledgeBase/install-node--npm-yarn.txt

+
+## install node
+curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -
+apt-get install -y nodejs
+npm install npm --global
+
+check version: 
+node -v (or nodejs -v)
+npm -v
+
+## install yarn (after node)
+curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -curl -sL https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update && sudo apt-get install yarn
+
+

common/docs/knowledgeBase/orientdb-3-migration.txt

+ORIENT 3 MIGRATION:
+
+[creating the new spatial property and index]
+CREATE PROPERTY Entity.loc EMBEDDED OPoint
+CREATE INDEX Entity.loc ON Entity(loc) SPATIAL ENGINE LUCENE
+
+
+update Entity SET location = {"@class": "OPoint","coordinates" : [-83.353095,42.469501]} where @rid='#14:0'
+
+[delete duplicates by id - old database]
+delete vertex Entity where id in (select id from (select from (select id,count(*) from Entity group by id) where count > 1))
+

common/docs/knowledgeBase/python3-starter.txt

+Python 3 starter:
+
+
+sudo apt install python3 python3-dev python3-pip python3-tk
+
+- create virtual env]
+python3 -m venv [my-working-directory]
+- activate virtual env
+source [my-working-directory]/bin/activate
+
+- install tensorflow
+pip3 install --upgrade tensorflow
+
+- in vscode
+  settings.json :
+  {
+    "python.pythonPath": "[path/to/your/venv/bin]"
+  }
+- when existing env:
+deactivate
+