docs: lots of minor language polish

Mostly based on recent language decisions from "everything curl":

- remove contractions (isn't => is not)
- *an* HTTP (consistency)
- runtime (no hyphen)
- backend (no hyphen)
- URL is uppercase

Closes #8646

docs/TheArtOfHttpScripting.md

@@ -30,7 +30,7 @@
  request a particular action, and then the server replies a few text lines
  before the actual requested content is sent to the client.
 
- The client, curl, sends a HTTP request. The request contains a method (like
+ The client, curl, sends an HTTP request. The request contains a method (like
  GET, POST, HEAD etc), a number of request headers and sometimes a request
  body. The HTTP server responds with a status line (indicating if things went
  well), response headers and most often also a response body. The "body" part
@@ -103,7 +103,7 @@
  The port number you specify in the URL is the number that the server uses to
  offer its services. Sometimes you may use a proxy, and then you may
  need to specify that proxy's port number separately from what curl needs to
- connect to the server. Like when using a HTTP proxy on port 4321:
+ connect to the server. Like when using an HTTP proxy on port 4321:
 
     curl --proxy http://proxy.example.org:4321 http://remote.example.org/
 
@@ -207,7 +207,7 @@
 
 ## Forms explained
 
- Forms are the general way a website can present a HTML page with fields for
+ Forms are the general way a website can present an HTML page with fields for
  the user to enter data in, and then press some kind of 'OK' or 'Submit'
  button to get that data sent to the server. The server then typically uses
  the posted data to decide how to act. Like using the entered words to search
@@ -351,11 +351,11 @@
 
 ## PUT
 
- Perhaps the best way to upload data to a HTTP server is to use PUT. Then
+ Perhaps the best way to upload data to an HTTP server is to use PUT. Then
  again, this of course requires that someone put a program or script on the
- server end that knows how to receive a HTTP PUT stream.
+ server end that knows how to receive an HTTP PUT stream.
 
- Put a file to a HTTP server with curl:
+ Put a file to an HTTP server with curl:
 
     curl --upload-file uploadfile http://www.example.com/receive.cgi
 
@@ -386,8 +386,8 @@
 
 ## Proxy Authentication
 
- Sometimes your HTTP access is only available through the use of a HTTP
- proxy. This seems to be especially common at various companies. A HTTP proxy
+ Sometimes your HTTP access is only available through the use of an HTTP
+ proxy. This seems to be especially common at various companies. An HTTP proxy
  may require its own user and password to allow the client to get through to
  the Internet. To specify those with curl, run something like:
 
@@ -416,7 +416,7 @@
 
 ## Referer
 
- A HTTP request may include a 'referer' field (yes it is misspelled), which
+ An HTTP request may include a 'referer' field (yes it is misspelled), which
  can be used to tell from which URL the client got to this particular
  resource. Some programs/scripts check the referer field of requests to verify
  that this was not arriving from an external site or an unknown page. While
@@ -560,7 +560,7 @@
 
  Curl supports encrypted fetches when built to use a TLS library and it can be
  built to use one out of a fairly large set of libraries - `curl -V` will show
- which one your curl was built to use (if any!). To get a page from a HTTPS
+ which one your curl was built to use (if any!). To get a page from an HTTPS
  server, simply run curl like:
 
     curl https://secure.example.com
@@ -572,7 +572,7 @@
  side certificates. All certificates are locked with a pass phrase, which you
  need to enter before the certificate can be used by curl. The pass phrase
  can be specified on the command line or if not, entered interactively when
- curl queries for it. Use a certificate with curl on a HTTPS server like:
+ curl queries for it. Use a certificate with curl on an HTTPS server like:
 
     curl --cert mycert.pem https://secure.example.com