As a Wikidata editor I want other editors to check if the Lexeme they are about to create already exists in order to prevent duplicates.
**Problem:**
We need to encourage checking for existing Lexemes before creating new ones.
**Screenshots/mockups:**
https://www.figma.com/file/XoYktoKEBnC0VIf1SRuxJK/Lexicographical-Data-UI?node-id=493%3A3179
**Acceptance criteria:**
[ ] a sentence is shown below the headline with some instructions for checking for existing Lexemes
[ ] the search link links to advanced search with namespace restrictions already taken into account (see link below)
[ ] if a Lemma was already entered then the search link uses that Lemma for the search (see link below)
**Notes:**
* Copy: You can check whether a Lexeme already exists by using the search. You can also learn more about Lexemes in the help box below.
* The search part of the text links to Advanced search with search in Lexeme namespace already selected: ‘https://www.wikidata.org/w/index.php?search=&title=Special:Search&profile=advanced&fulltext=1&ns146=1’ and if the user had entered a Lemma then we use it in the search directly: https://www.wikidata.org/w/index.php?search=&title=Special:Search&profile=advanced&fulltext=1&ns146=1&search=foo