[Doc] Mail process of canap

Close #52 (closed)

Documentation/Mail_process.md

+# Mail process of canap
+
+## As an applicant 
+```mermaid
+graph LR
+    A[Form] -->B(Form completed)
+    B-->|Send mail to| D[The 'Formation apprentis']
+    B-->|Send mail to| E[The applicant]
+```
+
+## As a responsible 
+```mermaid
+graph LR
+    A[Gest -> API] -->B(Answer with the selected response)
+    B-->|Send mail to| D[The applicant]
+    B-->|Send mail to| E[The 'formation apprentis' in Bcc/CC to ]
+```