[INTERNAL] Modified .gitignore for ui5-schemas and ui5-codecompletion
[INTERNAL] Modified .gitignore for ui5-schemas and ui5-codecompletion

To exclude default target directories of those two npm packages.
- https://github.com/ui5experts/ui5-schemas
- https://github.com/vobujs/ui5-codecompletion
- Directory for ui5-codecompletion was already excluded; made the comment for it clearer.

Change-Id: Ia29f08ddb2b546a4adc195e1705cea3a7bcf1fc8

SQCLabs/openui5,cschuff/openui5,SAP/openui5,nzamani/openui5,SAP/openui5,cschuff/openui5,nzamani/openui5,SQCLabs/openui5,SQCLabs/openui5,nzamani/openui5,SAP/openui5,SAP/openui5,cschuff/openui5