Replace "container's main process" with "container process"

We use both forms, but the latter was more popular.  Before this
branch:

  $ git grep -i 'container process' origin/master | wc -l
  13
  $ git grep -i 'main process' origin/master | wc -l
  4

Also fix "process id" -> "process ID" in one of the lines I touched,
to match fork(2) [1].

[1]: http://man7.org/linux/man-pages/man2/fork.2.html

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

runtime.md

@@ -20,7 +20,7 @@ The value MAY be one of:
     * `stopped` : the container has been created and the user-specified code has been executed but is no longer running
 
   Additional values MAY be defined by the runtime, however, they MUST be used to represent new runtime states not defined above.
-* **`pid`**: (int) is the ID of the main process within the container, as seen by the host.
+* **`pid`**: (int) is the ID of the container process, as seen by the host.
 * **`bundlePath`**: (string) is the absolute path to the container's bundle directory.
 This is provided so that consumers can find the container's configuration and root filesystem on the host.
 * **`annotations`**: (map) contains the list of annotations associated with the container.

specs-go/config.go

@@ -53,8 +53,8 @@ type Process struct {
 	SelinuxLabel string `json:"selinuxLabel,omitempty" platform:"linux"`
 }
 
-// User specifies Linux/Solaris specific user and group information for the container's
-// main process.
+// User specifies Linux/Solaris specific user and group information
+// for the container process.
 type User struct {
 	// UID is the user id. (this field is platform dependent)
 	UID uint32 `json:"uid" platform:"linux,solaris"`

specs-go/state.go

@@ -8,7 +8,7 @@ type State struct {
 	ID string `json:"id"`
 	// Status is the runtime state of the container.
 	Status string `json:"status"`
-	// Pid is the process id for the container's main process.
+	// Pid is the process ID for the container process.
 	Pid int `json:"pid"`
 	// BundlePath is the path to the container's bundle directory.
 	BundlePath string `json:"bundlePath"`