Fixed typo in DEVELOPER_GUIDE.md. (opensearch-project#12051)

Signed-off-by: Thomas Seidl <[email protected]>

DEVELOPER_GUIDE.md

@@ -348,7 +348,7 @@ Please follow these formatting guidelines:
 * Wildcard imports (`import foo.bar.baz.*`) are forbidden and will cause the build to fail.
 * If *absolutely* necessary, you can disable formatting for regions of code with the `// tag::NAME` and `// end::NAME` directives, but note that these are intended for use in documentation, so please make it clear what you have done, and only do this where the benefit clearly outweighs the decrease in consistency.
 * Note that JavaDoc and block comments i.e. `/* ... */` are not formatted, but line comments i.e `// ...` are.
-* There is an implicit rule that negative boolean expressions should use the form `foo == false` instead of `!foo` for better readability of the code. While this isn't strictly enforced, if might get called out in PR reviews as something to change.
+* There is an implicit rule that negative boolean expressions should use the form `foo == false` instead of `!foo` for better readability of the code. While this isn't strictly enforced, it might get called out in PR reviews as something to change.
 
 ## Adding Dependencies