fixing usernmae typo to username

src/docs/asciidoc/index.adoc

@@ -1387,7 +1387,7 @@ It is possible to specify an alternative authentication mechanism by supplying a
 ====== TLS
 Spring LDAP provides two different configuration options for LDAP servers requiring TLS secure channel communication: `DefaultTlsDirContextAuthenticationStrategy` and `ExternalTlsDirContextAuthenticationStrategy`.
 Both these implementations will negotiate a TLS channel on the target connection, but they differ in the actual authentication mechanism.
-Whereas the `DefaultTlsDirContextAuthenticationStrategy` will apply SIMPLE authentication on the secure channel (using the specified `usernmae` and `password`), the `ExternalTlsDirContextAuthenticationStrategy` will use EXTERNAL SASL authentication, applying a client certificate configured using system properties for authentication.
+Whereas the `DefaultTlsDirContextAuthenticationStrategy` will apply SIMPLE authentication on the secure channel (using the specified `username` and `password`), the `ExternalTlsDirContextAuthenticationStrategy` will use EXTERNAL SASL authentication, applying a client certificate configured using system properties for authentication.
 
 Since different LDAP server implementations respond differently to explicit shutdown of the TLS channel (some servers require the connection be shutdown gracefully; others do not support it), the TLS `DirContextAuthenticationStrategy` implementations support specifying the shutdown behavior using the `shutdownTlsGracefully` parameter. If this property is set to `false` (the default), no explicit TLS shutdown will happen; if it is `true`, Spring LDAP will try to shutdown the TLS channel gracefully before closing the target context.