Increase documentation of HttpUrl.Builder (#4983)
Increase documentation of HttpUrl.Builder (#4983)

* Increase documentation of HttpUrl.Builder

Add documentation for the `HttpUrl.newBuilder()` method indicating that initial values are read from the existing URL, and for `HttpUrl.Builder.scheme` indicating the legal values for the `scheme` parameter

* Quote the possible values of scheme in Javadoc

* Fix puncuation on scheme and newBuilder JavaDoc

ze-pequeno/okhttp,ze-pequeno/okhttp,cketti/okhttp,square/okhttp,cketti/okhttp,square/okhttp,cketti/okhttp,ansman/okhttp,yschimke/okhttp,cmzy/okhttp,ansman/okhttp,tiarebalbi/okhttp,ze-pequeno/okhttp,square/okhttp,tiarebalbi/okhttp,yschimke/okhttp,yschimke/okhttp,tiarebalbi/okhttp,ansman/okhttp,cmzy/okhttp