Base: Add 2 manual pages to describe the ProcFS and SysFS

Base/usr/share/man/man7/proc.md

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+## Name
+
+proc - SerenityOS ProcFS
+
+## Description
+
+The kernel can expose process related information in /proc.
+This functionality is used by various userland programs.
+Most of the output layout in the ProcFS nodes is JSON.
+
+### Global entries
+
+* **`all`** - this node exports a list of all processes that currently exist.
+* **`cmdline`** - this node exports the kernel boot commandline that was passed to
+from the bootloader.
+* **`cpuinfo`** - this node exports information on the CPU.
+* **`devices`** - this node exports information on all devices that might be represented
+by a device file.
+* **`df`** - this node exports information on mounted filesystems and basic statistics on
+them.
+* **`dmesg`** - this node exports information from the kernel log.
+* **`interrupts`** - this node exports information on all IRQ handlers and basic statistics on
+them. 
+* **`kernel_base`** - this node reveals the loading address of the kernel.
+* **`keymap`** - this node exports information on current used keymap.
+* **`memstat`** - this node exports statistics on memory allocation in the kernel.
+* **`pci`** - this node exports information on all currently-discovered PCI devices in the system.
+
+### `net` directory
+
+* **`adapters`** - this node exports information on all currently-discovered network adapters.
+* **`arp`** - this node exports information on the kernel ARP table.
+* **`local`** - this node exports information on local (unix) sockets.
+* **`tcp`** - this node exports information on tcp sockets.
+* **`udp`** - this node exports information on udp sockets.
+
+### `sys` directory
+
+This subdirectoy includes global settings of the kernel.
+
+* **`caps_lock_to_ctrl`** - this node controls remapping of of caps lock to the Ctrl key.
+* **`kmalloc_stacks`** - this node controls whether to send information about kmalloc to debug log.
+* **`ubsan_is_deadly`** - this node controls the deadliness of the kernel undefinied behavior
+sanitizer errors.
+
+### Per process entries
+
+* **`cwd`** - a symbolic link to current work directory of a process.
+* **`exe`** - a symbolic link to the executable binary of the process.
+* **`fds`** - this node exports information on all currently open file descriptors.
+* **`fd`** - this directory lists all currently open file descriptors.
+* **`perf_events`** - this node exports information being gathered during a profile on a process.
+* **`pledge`** - this node exports information on all the pledge requests and promises of a process.
+* **`stacks`** - this directory lists all stack traces of process threads.
+* **`pledge`** - this node exports information on all the unveil requests of a process.
+* **`vm`** - this node exports information on virtual memory mappings of a process.
+
+### Consistency and stability of data across multiple read operations
+
+When opening a data node, the kernel generates the required data so it's prepared
+for read operation when requested to. However, in order to ensure that multiple reads
+will not create a corrupted data from that data node, a read operation alone will
+not inquire the kernel to refresh the data.
+To keep data output being refreshed, the userland has to re-open the data node with a 
+new file descriptor, or to perform the `lseek` syscall on the open file descriptor to
+reset the the offset to 0.
+
+## See also
+
+* [`mount`(2))](../man2/mount.md).
+* [`boot_parameters`(7))](boot_parameters.md).
+* [`pledge`(2))](../man2/pledge.md).
+* [`unveil`(2))](../man2/unveil.md).

Base/usr/share/man/man7/sys.md

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+## Name
+
+sys - SerenityOS SysFS
+
+## Description
+
+The kernel can expose system (kernel, firmware and hardware) related information in /sys.
+
+### `bus` directory
+
+This directory include a subdirectory for each discovered and registered bus in the system.
+
+Possible busses to be exposed in this directory are:
+1. The `pci` subdirectory that includes all discovered PCI devices as subdirectories.
+The subdirectories of the PCI devices include files with basic information on the devices.
+2. The `usb` subdirectory that includes all discovered USB devices as files.
+The files of the USB devices export basic information on the devices.
+
+### `dev` directory
+
+This directory include two subdirectories - `block` and `char`, each for block
+and character devices respectively. The files in these subdirectories are not
+device files, but merely a file with filename layout of "major:minor", to aid
+userspace in generating the appropriate device files.
+
+### `firmware` directory
+
+This directory include two subdirectories - `acpi` and `bios`.
+The `bios` subdirectory maintains files of the exposed SMBIOS blobs, if present
+by the firmware.
+The `acpi` subdirectory maintains files of the exposed ACPI tables, if present
+by the firmware.
+A file called `power_state` is responsible for power state switching.
+
+#### `power_state`
+
+This file only responds to write requests on it. A written value of `1` results
+in system reboot. A written value of `2` results in system shutdown.
+
+### Consistency and stability of data across multiple read operations
+
+When opening a data node, the kernel generates the required data so it's prepared
+for read operation when requested to. However, in order to ensure that multiple reads
+will not create a corrupted data from that data node, a read operation alone will
+not inquire the kernel to refresh the data.
+To keep data output being refreshed, the userland has to re-open the data node with a 
+new file descriptor, or to perform the `lseek` syscall on the open file descriptor to
+reset the the offset to 0.
+
+## See also
+
+* [`mount`(2))](../man2/mount.md).