Add colors for gitlab actions

simplified-process.md

 ```mermaid
 graph TB
+  style gitlab fill:#817a65,stroke:#333,stroke-width:3px
   start("Start")
   reserve["Reserve 'contribution name' in portal"]
   createBranch["Create contribution branch<br />named as 'contribution name' "]
@@ -24,32 +25,32 @@ graph TB
   conflict{"Is there any conflict?"}
   fixConflict["Rebase contribution branch/fix conflict"]
   start-->reserve
-  reserve-->createBranch
-  createBranch-->submitChanges
-  hasComments-->submitChanges
-  submitChanges-->isReady
-  isReady--Ready-->blockContribution
-  blockContribution-->existsMR
+  reserve-->gitlab(createBranch)
+  gitlab(createBranch)-->gitlab(submitChanges)
+  hasComments-->gitlab(submitChanges)
+  gitlab(submitChanges)-->isReady
+  isReady--Ready-->gitlab(blockContribution)
+  gitlab(blockContribution)-->existsMR
   existsMR--Yes-->uploadCR
-  existsMR--No-->submitContrib
-  isReady--"comments or not finished"-->submitChanges
+  existsMR--No-->gitlab(submitContrib)
+  isReady--"comments or not finished"-->gitlab(submitChanges)
   uploadCR-->revision
-  submitContrib-->uploadCR
+  gitlab(submitContrib)-->uploadCR
   revision-->approval
   approval--Yes-->approve
   approval--No-->reject
-  approve-->applyMR
-  applyMR-->conflict
-  approval--"Revision required"-->reviseContrib
-  reviseContrib-->unlockMR
-  unlockMR-->submitChanges
-  reject-->closeMR
-  closeMR-->stop
+  approve-->gitlab(applyMR)
+  gitlab(applyMR)-->conflict
+  approval--"Revision required"-->gitlab(reviseContrib)
+  gitlab(reviseContrib)-->gitlab(unlockMR)
+  gitlab(unlockMR)-->gitlab(submitChanges)
+  reject-->gitlab(closeMR)
+  gitlab(closeMR)-->stop
   conflict--No-->newBaseline
-  conflict--Yes-->fixConflict
-  fixConflict-->revision
-  newBaseline--Yes-->makeBaseline
+  conflict--Yes-->gitlab(fixConflict)
+  gitlab(fixConflict)-->revision
+  newBaseline--Yes--gitlab(makeBaseline)
   newBaseline--No-->stop
-  makeBaseline-->stop
+  gitlab(makeBaseline)-->stop
 ```