Manual tidy up

[Danack]

Hi, just though you might like to know there are two systemic issues with the documentation:

i) using the 'continuing' form of verbs like "It is being" is not idiomatic English in most countries.

ii) Use of 'an' instead of 'a' .

Some examples:

https://www.froala.com/wysiwyg-editor/docs/sdks/php/file-s3-upload
s/When an file/When a file/
s/it is being sent directly to the S3/it is sent directly to the S3/

https://www.froala.com/wysiwyg-editor/docs/sdks/php/image-server-upload
s/they are being stored there only/ they are stored there only/

https://www.froala.com/wysiwyg-editor/docs/sdks/php/image-resize
s/comes with the possibility to resize the image when it is being stored on the disk/comes with the possibility to resize the image when it is stored on the disk/
s/It is using the / It uses the/

This isn't hugely important, but makes the documentation slightly harder to read than it needs to be.