docs: change sub-domain to subdomain

https://en.wikipedia.org/wiki/Subdomain

Closes #11793

docs/MANUAL.md

@@ -796,7 +796,7 @@ such place might be: [RFC 2255, The LDAP URL
 Format](https://curl.se/rfc/rfc2255.txt)
 
 To show you an example, this is how to get all people from an LDAP server that
-has a certain sub-domain in their email address:
+has a certain subdomain in their email address:
 
     curl -B "ldap://ldap.frontec.se/o=frontec??sub?mail=*sth.frontec.se"
 

docs/cmdline-opts/cookie.d

@@ -34,7 +34,7 @@ written to the file. To store cookies, use the --cookie-jar option.
 
 If you use the Set-Cookie file format and do not specify a domain then the
 cookie is not sent since the domain will never match. To address this, set a
-domain in Set-Cookie line (doing that will include sub-domains) or preferably:
+domain in Set-Cookie line (doing that will include subdomains) or preferably:
 use the Netscape format.
 
 Users often want to both read cookies from a file and write updated cookies

docs/cmdline-opts/url.d

@@ -13,7 +13,7 @@ Specify a URL to fetch. This option is mostly handy when you want to specify
 URL(s) in a config file.
 
 If the given URL is missing a scheme name (such as "http://" or "ftp://" etc)
-then curl will make a guess based on the host. If the outermost sub-domain
+then curl will make a guess based on the host. If the outermost subdomain
 name matches DICT, FTP, IMAP, LDAP, POP3 or SMTP then that protocol will be
 used, otherwise HTTP will be used. Since 7.45.0 guessing can be disabled by
 setting a default protocol, see --proto-default for details.

docs/libcurl/curl_url_set.3

@@ -151,7 +151,7 @@ are set.
 .IP CURLU_GUESS_SCHEME
 If set, allows the URL to be set without a scheme and it instead "guesses"
 which scheme that was intended based on the host name. If the outermost
-sub-domain name matches DICT, FTP, IMAP, LDAP, POP3 or SMTP then that scheme
+subdomain name matches DICT, FTP, IMAP, LDAP, POP3 or SMTP then that scheme
 is used, otherwise it picks HTTP. Conflicts with the
 \fICURLU_DEFAULT_SCHEME\fP option which takes precedence if both are set.
 .IP CURLU_NO_AUTHORITY

docs/libcurl/opts/CURLOPT_COOKIEFILE.3

@@ -50,7 +50,7 @@ see \fICURLOPT_COOKIEJAR(3)\fP.
 If you read cookies from a plain HTTP headers file and it does not specify a
 domain in the Set-Cookie line, then the cookie is not sent since the cookie
 domain cannot match the target URL's. To address this, set a domain in
-Set-Cookie line (doing that includes sub-domains) or preferably: use the
+Set-Cookie line (doing that includes subdomains) or preferably: use the
 Netscape format.
 
 If you use this option multiple times, you add more files to read cookies

docs/libcurl/opts/CURLOPT_COOKIELIST.3

@@ -47,7 +47,7 @@ domain, then the cookie is sent for any domain (even after redirects are
 followed) and cannot be modified by a server-set cookie. If a server sets a
 cookie of the same name (or maybe you have imported one) then both are sent on
 future transfers to that server, likely not what you intended. To address
-these issues set a domain in Set-Cookie (doing that includes sub-domains) or
+these issues set a domain in Set-Cookie (doing that includes subdomains) or
 much better: use the Netscape file format.
 
 Additionally, there are commands available that perform actions if you pass in

docs/libcurl/opts/CURLOPT_URL.3

@@ -46,7 +46,7 @@ started. Even if you set a crazy value here, \fIcurl_easy_setopt(3)\fP might
 still return \fICURLE_OK\fP.
 
 If the given URL is missing a scheme name (such as "http://" or "ftp://" etc)
-then libcurl guesses based on the host. If the outermost sub-domain name
+then libcurl guesses based on the host. If the outermost subdomain name
 matches DICT, FTP, IMAP, LDAP, POP3 or SMTP then that protocol gets used,
 otherwise HTTP is used. Since 7.45.0 guessing can be disabled by setting a
 default protocol, see \fICURLOPT_DEFAULT_PROTOCOL(3)\fP for details.