Rectify incorrect sanitizing regex example provided in how-to docs

[dharley-gaggle]

the spring-boot actuator documentation located at https://docs.spring.io/spring-boot/docs/2.1.x/reference/html/howto-actuator.html gives an incorrect regex example. stating: "It is also possible to use a regular expression instead, such as *credentials.* to sanitize any key that holds the word credentials as part of the key."
however, if done via code, such a regex (am targeting password for my development purposes, not credentials) generates an exception at startup: java.util.regex.PatternSyntaxException, dangling metacharacter '*'
and if done via application.yml property the application will not start, giving exception: org.yaml.snakeyaml.composer.ComposerException","exception_message":"found undefined alias password.*\n in 'reader', line 54, column 25:\n keys-to-sanitize: *password.*\n
the correct example for such a regex should be: .*credentials.*