☂️ Update documentation according to our new policy

[iDneprov]

Code examples should be in tests

• [x] #305
• [x] #312
• [x] #306
• [x] #307
• [x] #348
• [x] #349
• [x] #185
• [x] #354
• [x] #142
• [x] #308
• [x] #309
• [x] #91

May be later

• [x] #310
• [ ] #155
• [x] #205
• [ ] #227

[dkasimovskiy]

Double check ticket description https://github.com/tarantool/cartridge-java/issues/185 It's possible a duplicate of existing ones in this epic.