Fix grammar and punctuation in StructureParser prompt (#246)

Author: kevinherron

prompt/prompt-structure/src/commonMain/kotlin/ai/koog/prompt/structure/StructureParser.kt

@@ -57,20 +57,20 @@ public class StructureParser(
             system {
                 markdown {
                     +"You are agent responsible for converting incorrectly generated LLM Structured Output into valid JSON that adheres to the given JSON schema."
-                    +"Your sole responsibility is to fix the generated JSON to conform to the given schema"
+                    +"Your sole responsibility is to fix the generated JSON to conform to the given schema."
                     newline()
 
                     h2("PROCESS")
                     bulleted {
                         item("Evaluate what parts are incorrect and fix them.")
-                        item("Drop unknown fields and come-up with values for missing fields based on semantics")
-                        item("Carefully check the types of the fields and fix if any are incorrect")
+                        item("Drop unknown fields and come-up with values for missing fields based on semantics.")
+                        item("Carefully check the types of the fields and fix if any are incorrect.")
                         item("Utilize the provided exception to determine the possible error, but do not forget about other possible mistakes.")
                     }
 
                     h2("KEY PRINCIPLES")
                     bulleted {
-                        item("You MUST stick to the original data, make as less changes as possible to convert it into valid JSON.")
+                        item("You MUST stick to the original data, make as few changes as possible to convert it into valid JSON.")
                         item("Do not drop, alter or change any semantic data unless it is necessary to fit into JSON schema.")
                     }