Update SQL Roadmap UPDATE Statement Node. (#6784)

* Fill update node with info 

Add relevant info.
Any new proposals welcome

* remove emoji and code formatting as suggested in PR review

src/data/roadmaps/sql/content/update@eu9dJFi6gBPMBdy08Y5Bb.md

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+# UPDATE
+
+The `UPDATE` statement is used to modify existing data in a given table. <br/>
+It can be done so with the query
+
+```
+UPDATE table_name
+SET column1 = value1, column2 = value2, ...
+WHERE condition;
+```
+
+- _Keep in mind that **SET** and **WHERE** are also commands to assign a new value(SET) only if the condition is met(WHERE)_
+
+Omitting the `WHERE` clause will update **all** rows in the table.
+
+Visit the following resources to learn more:
+
+- [@article@W3Schools SQL UPDATE Statement Doc](https://www.w3schools.com/sql/sql_update.asp)