Do another pass at README / User Guide for 2.x

[gaearon]

For example see #5103 (comment). We should just re-read the whole thing. Also possibly add link to 1.x version of User Guide at the top.

[gaearon]

• proxy changeOrigin set to true by default #4302 (comment)

[gaearon]

• https://mobile.twitter.com/juffalow/status/1045254667721224192

[gaearon]

• Move browsers to cross-tool config #3644 (comment)

[mareksuscak]

Documented SVGs as React components in #5147.

[ArmanNisch]

It also seems like the Configuring the Proxy Manually (line 1098) is not updated to the new way of configuring advanced proxies (i.e. CRA 2.0 now makes use of setupProxy.js)

[ArmanNisch]

There might be a duplication of information or at the very least the two below listed headings should probably be shown next to each other, as in my opinion, they both convey information relating to the same topic:

Line 833: The environment variables are embedded during the build time

Line 2047: Customizing Environment Variables for Arbitrary Build Environments

[mareksuscak]

It also seems like the Configuring the Proxy Manually (line 1098) is not updated to the new way of configuring advanced proxies (i.e. CRA 2.0 now makes use of setupProxy.js)

The guide has recently been updated but lives in the next branch, all links point to master (URLs are not relative, can we make them be relative?)

You can find the updated section here.

[Timer]

next is no longer kept up to date. All changes are in master.

It also seems like the Configuring the Proxy Manually (line 1098) is not updated to the new way of configuring advanced proxies (i.e. CRA 2.0 now makes use of setupProxy.js)

This is updated. You must be looking at an old version?

[gaearon]

#4903 (comment)

[gaearon]

Should also document #5140

[gaearon]

#5103 (comment)