fix: add unique keys for people lists

Author: BakasaRus

docs/before/entry_test.md

@@ -59,7 +59,7 @@
 import Person from '@site/src/components/person';
 import { entryStaff } from '@site/src/utils/staff';
 
-{entryStaff.map(person => <Person {...person}/>)}
+{entryStaff.map(person => <Person key={person.email} {...person}/>)}
 
 ## Английский язык
 

docs/department.md

@@ -10,7 +10,7 @@ sidebar_position: 3
 import Person from '@site/src/components/person';
 import { mainStaff } from '@site/src/utils/staff';
 
-{mainStaff.map(person => <Person {...person}/>)}
+{mainStaff.map(person => <Person key={person.email} {...person}/>)}
 
 ## Студенческий офис (Студофис, СО)